Polyester resin, molded product made thereof and process for production of polyester resin

ABSTRACT

A polyester resin produced by polycondensing a dicarboxylic acid component containing an aromatic dicarboxylic acid or its ester-forming derivative as the main component and a diol component containing ethylene glycol as the main component in the presence of at least an antimony compound and a phosphorus compound, via an esterification reaction or an ester exchange reaction, which is characterized in that the amount of antimony eluted when immersed in hot water of 95° C. for 60 minutes in the form of particles having a number average particle weight of 24 mg, is not more than 1 μg per 1 g of the polyester resin, as antimony atoms (Sb).

This application is a Continuation of International Application No.PCT/JP02/00562, filed Jan. 25, 2002.

TECHNICAL FIELD

The present invention relates to a polyester resin poly-condensed in thepresence of an antimony compound which is to be used for molding of e.g.bottles, films, sheets and fibers, and a process for its production.More particularly, it relates to a polyester resin having the elution ofantimony suppressed during the contact with water, solvent, etc., in aposttreatment step after the polycondensation, in a dying step afterprocessed into polyester fibers and at the time of filling a content asused as a polyester container, etc.

BACKGROUND ART

Heretofore, a polyester resin such as a polyethylene terephthalate resinhas been widely used as various packaging materials such as containersor films, or as fibers, etc., since it is excellent in mechanicalstrength, chemical stability, gas barrier property, hygienics, etc., andis relatively inexpensive and light in weight.

Such a polyester resin is produced mainly by using an antimony compoundas a polycondensation catalyst. However, there has been concern about aproblem such that the antimony compound or metal antimony remaining inthe resin may elute, for example, in a step of being contacted withwater for e.g. cooling after the polycondensation or in a step of beingcontacted with a solvent for e.g. dying after being processed intofibers, thus causing environmental pollution. Further, there has beenconcern about a possibility that in use as a packaging material for e.g.a container, it will elute from the container, for example, in a step ofbeing contacted with hot water for e.g. heat sterilizing filling.Accordingly, various polyester resins have been proposed which areproduced, for example, by using a titanium compound as apolycondensation catalyst instead of the antimony compound or using atitanium compound in combination therewith. However, there has been aproblem such that the color tone of the polyester resin deteriorates,acetaldehyde, diethylene glycol, etc. will form, whereby the amount ofsuch by-products in the polyester resin increases, or elution ofantimony from the polyester resin cannot adequately be suppressed.

Meanwhile, when a polyester resin or the like is used for a hollowcontainer for a beverage, it may be used, for example, for anon-carbonated beverage such as mineral water, tea or juice, or for acarbonated beverage. Further, irrespective of the non-carbonated orcarbonated beverage, an unheated aseptic filling method and a heatsterilization filling method are available as methods for filling thebeverage.

A conventional polyester resin obtainable by using an antimony compoundas a catalyst has a high crystallization rate, whereby the transparencytends to be poor. Accordingly, especially when it is used for a hollowcontainer for a non-carbonated beverage, it is common to suppress thecrystallization rate to a proper level by copolymerizing e.g. diethyleneglycol-isophthalic acid in a small amount and usually setting themolecular weight (usually represented by the intrinsic viscosity) of theresin to be relatively high, in order to form a container such as abottle excellent in transparency. However, since a copolymer componentis incorporated, there is a problem such that oriented crystallizationwill not adequately proceed at the time of molding, whereby it tends tobe difficult to obtain a molded product having sufficient heatresistance and strength efficiently, and when formed into a moldedproduct, the amount of by-products such as acetaldehyde contained in themolded product tends to increase. If the molecular weight is furtherincreased, there has been a problem such that the productivity of theresin and the productivity in the molding tend to deteriorate, or theamount of by-products such as acetaldehyde tends to further increase.

Further, with a conventional polyester resin obtainable by using anantimony compound as a catalyst, the crystallization rate is high, andaccordingly, it is common to carry out copolymerization of acorresponding amount of diethylene glycol as mentioned above, wherebythe transparency when formed into a. container may be improved, but in acase where it is used as a bottle particularly for a carbonatedbeverage, which is transported in a state where a stress is exerted bythe inner pressure of the contained beverage, there has been a problemthat cracks are likely to form by external factors such as theenvironmental temperature, chemical agents or solvents.

For the purpose of e.g. imparting environmental stress crackingresistance to a bottle for a carbonated beverage, a method ofcopolymerizing a polyfunctional compound component (e.g. JP-A-5-84808)or a method of applying anneal treatment to a bottle (e.g.JP-A-6-297550) has, for example, been proposed. However, such methodsare not necessarily satisfactory from the viewpoint of the thermalstability during the production of a bottle, the transparency as abottle or the productivity of the bottle.

Further, with a conventional polyester resin obtainable by using anantimony compound as a catalyst, the crystallization rate is so highthat when a bottle obtained by molding it, is used particularly for heatsterilization filling, there has been a problem that deterioration ofthe transparency of a preform by heat treatment before blowing at thetime of molding a bottle, tends to be remarkable. Accordingly, therehave been many proposals from the viewpoint of the polycondensationcatalyst, such as a method of using a titanium compound or a germaniumcompound, and further a magnesium compound and a phosphorus compound, incombination with the antimony compound, as a polycondensation catalyst.However, according to the study by the present inventors, it has beenfound that although in each proposal, the effect of lowering thecrystallization rate is observed, there has been a problem that theabove-mentioned heat treatment at the time of molding a bottle, takestime and there will be a difference between local crystallization rates,for example, between inside and outside of the mouth stopper portion,whereby the dimensional precision at the mouth stopper portion cannot bestabilized.

Further, with a conventional polyester resin obtainable by using anantimony compound as a catalyst, the crystallization rate is so highthat there has been a problem that at the time of molding a bottle, inthe injection molding of a preform, it is necessary to set the moldingtemperature at a high level for melting and plasticizing, followed byinjection into a mold and by quenching in order to maintain thetransparency, and the molding temperature is obliged to be high,consequently, by-products such as acetaldehyde, cyclic low molecularweight products, etc. will form in the resin after the molding, and suchacetaldehyde may adversely affect the taste of the content when used asa bottle, or such cyclic low molecular weight products tend tocontaminate the blow molding mold, whereby for the cleaning of the mold,the productivity will substantially be reduced.

Further, in order to solve the above-mentioned various problems, variousproposals have been made for a process for producing a polyester resinwherein the amount of the antimony is reduced, and a titanium compoundor a germanium compound, and further a magnesium compound and aphosphorus compound or the like are used in combination. However, by anyone of conventional methods, it is difficult to sufficiently suppresselution of antimony, and there has been a problem that theabove-mentioned other various problems cannot be adequately solved, orthe polymerizability deteriorates, whereby the productivity of thepolyester resin tends to be poor.

For example, JP-A-9-87374 discloses a process for producing athermoplastic polyester, characterized in that in the production of athermoplastic polyester resin comprising a dicarboxylic acid componentand an alkylene glycol component, a mixture of an antimony compound anda titanium compound, and at least one compound selected from alkalimetal compounds and alkaline earth metal compounds, are used as apolycondensation catalyst.

JP-A-2000-128964 discloses a polyester resin produced by using anantimony compound as a catalyst and containing ethylene terephthalate asthe main repeating unit, which is characterized in that the haze of amolded product having a thickness of 4 mm molded from this resin at atemperature of 290° C., is not more than 3.0%, and the haze of a moldedproduct having a thickness of 5 mm is not more than 15.0%.

Japanese Patent No. 03081104 discloses a polyester for forming a filmcomprising an aromatic dicarboxylic acid as the main acid component andan aliphatic glycol as the main glycol component, which is characterizedin that the content of metal-containing precipitated particles by acatalyst used at the time of synthesizing the polyester, is not morethan 0.01 wt % (based on the polyester), and the catalyst comprises atitanium compound or a titanium compound and an antimony compound, andthe amounts of these metal elements satisfy the specific ranges.JP-A-2000-219726, JP-A-2000-219730, JP-A-2000-226444, JP-A-2000-226445,JP-A-2000-226446 and JP-A-2000-226500 disclose polyester resinscontaining Sb and Ti or/and Ge as catalysts, and having densities anddensity-increasing rates within specific ranges.

However, according to the study by the present inventors, elution ofantimony is not adequately suppressed, and the polymerizability and theproductivity of the polyester resin are poor.

The present invention has been made in view of the above-described priorart, and it is an object of the present invention to provide a polyesterresin poly-condensed in the presence of an antimony compound and havingelution of antimony suppressed, and a process for producing a polyesterresin, whereby such a polyester resin can be obtained with goodpolymerizability and productivity.

DISCLOSURE OF THE INVENTION

The present invention has been made to accomplish the above object.Namely, the present invention relates to a polyester resin (hereinafterreferred to as polyester ({circle around (1)})) produced bypolycondensing a dicarboxylic acid component containing an aromaticdicarboxylic acid or its ester-forming derivative as the main componentand a diol component containing ethylene glycol as the main component inthe presence of at least an antimony compound and a phosphorus compound,via an esterification reaction or an ester exchange reaction, which ischaracterized in that the amount of antimony eluted when immersed in hotwater of 95° C. for 60 minutes in the form of particles having a numberaverage particle weight of 24 mg, is not more than 1 μg per 1 g of thepolyester resin, as antimony atoms (Sb).

By such present invention, elution of antimony can be suppressed, and apolyester resin having a good color tone and having formation ofby-products suppressed, can be provided.

One of preferred embodiments of the present invention is a polyesterresin (hereinafter referred to as polyester {circle around (2)}) whichis polyester {circle around (1)} wherein the ethylene glycol componentis at least 96 mol % of the total glycol component, the diethyleneglycol component is not more than 2.5 mol % of the total glycolcomponent, the terephthalic acid component is at least 98.5 mol % of thetotal acid component, the intrinsic viscosity IV is from 0.65 to 1.0dl/g, and the temperature-lowering crystallization temperature Tc₂ isfrom 150 to 200° C. According to this embodiment, even if thecopolymerized amount is particularly small and the intrinsic viscosityis low, the crystallization rate is low, whereby when formed into acontainer such as a bottle, it is possible to obtain a container havingexcellent transparency, heat resistance and strength at highproductivity, such being particularly suitable for a hollow containerfor a non-carbonized beverage such as mineral water, tea or juice.

Another preferred embodiment of the present invention is a polyesterresin (hereinafter referred to as polyester {circle around (3)}) whichis polyester {circle around (1)} and which contains an ethyleneterephthalate unit as the main repeating constituting unit and ischaracterized by satisfying the following characteristics (1), (2) and(3):

(1) after formed into a molded product, the temperature-risingcrystallization temperature (Tc₁) is at least 155° C., and thetemperature-lowering crystallization temperature (Tc₂) is at most 180°C. or not observed,

(2) the difference (ΔAA=AA_(s)−AA_(o)) between the acetaldehyde content(AA_(s); ppm) in a molded product after injection molding at 280° C. andthe acetaldehyde content (AA_(o); ppm) before the injection molding, isnot more than 15 ppm, and

(3) when an injection-molded sheet having a thickness of 1 mm isimmersed in a 0.2 wt % sodium hydroxide aqueous solution at 25° C. insuch a state that it is fixed along the outer circumference of acylinder having a diameter of 32mm, the environmental stress rupturetime is at least 10 minutes.

According to this embodiment, particularly, the transparency, strength,taste deterioration resistance of e.g. the contained beverage andenvironmental stress cracking resistance are good, such beingparticularly suitable for a bottle for a carbonated beverage.

Another preferred embodiment of the present invention is a polyesterresin (hereinafter referred to as polyester {circle around (4)}) whichis polyester {circle around (2)} or {circle around (3)} and which ischaracterized in that it contains a polyolefin resin or a polyamideresin in an amount of from 0.0001 to 1000 ppm, and after formed into amolded product, the temperature-rising crystallization temperature (Tc₁)is from 155 to 165° C., and the temperature-lowering crystallizationtemperature (Tc₂) is at most 180° C. or not observed. This embodimenthas a characteristic such that particularly when formed into a hollowcontainer, the transparency of the body portion will not deteriorate,and the crystallization rate at the mouth stopper portion is high,whereby the productivity of the hollow container is excellent, and thedimensional stability of the mouth stopper portion is excellent, andthere will be no substantial deformation of the mouth stopper portionduring hot filling, and it is suitable for a hollow container to be usedby heat sterilization filling irrespective of a non-carbonated beverageor a carbonated beverage.

Another preferred embodiment of the present invention is a polyesterresin (hereinafter referred to as polyester {circle around (5)}) whichis polyester {circle around (1)} and which is characterized in that thehaze in a thickness of 5 mm of a molded product after injection moldingat 270° C. is not more than 50%. According to this embodiment, even ifthe molding temperature is set to be lower than ever, molding ispossible without impairing the transparency, whereby a molded productexcellent also in transparency can be obtained while suppressingformation of acetaldehyde during the molding and suppressingcontamination of the mold during the molding, and thus it is suitablefor a hollow container irrespective of whether it is for anon-carbonated or carbonated beverage or whether it is for unheatedaseptic filling or for heat sterilization filling.

Another preferred embodiment of the present invention is a polyesterresin (hereinafter referred to as polyester {circle around (6)}) whichis polyester {circle around (1)} and which is characterized in that thenumber of particles of at least 1 μm in the interior of the resin is notmore than 20 particles/0.01 mm³. According to this embodiment, thenumber of particles in the interior of the resin is particularly small,whereby at the time of forming fibers or films, there will be nosubstantial thread breakage or film rupture caused by the particles, orwhen formed into a film, there will be no substantial projections suchas fish eyes on the surface, and thus, it is suitable for fibers andfilms.

Further, another gist of the present invention resides in a process forproducing a polyester resin, which comprises polycondensing adicarboxylic acid component containing an aromatic dicarboxylic acid orits ester-forming derivative as the main component and a diol componentcontaining ethylene glycol as the main component, characterized in thata catalyst is added to the reaction system so that the followingrespective atoms derived from the catalyst will be contained in thefollowing concentration ranges based on the obtainable polyester resin:

0<T≦50 ppm

10≦Sb≦250 ppm

0.1≦P≦200 ppm

6.0≦Sb/P≦30

(in the above formulae, T is the total concentration (ppm) of at leastone type of atoms selected from the group consisting of titanium atoms,hafnium atoms and zirconium atoms in the resin, Sb is the concentration(ppm) of antimony atoms in the resin, and P is the concentration (ppm)of phosphorus atoms in the resin). According to this invention, it ispossible to produce the polyester resin of the present invention havingelution of antimony suppressed, with good polymerizability andproductivity.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1: (a) is a plan view and (b) is a front view, of a stepped moldedplate for evaluation of the physical properties, molded in Examples.

FIG. 2: one embodiment of the apparatus for producing a polyester by theprocess of the present invention.

DESCRIPTION OF SYMBOLS

1 tank for preparation of a slurry

2 esterification reactor (first stage)

3 esterification reactor (second stage)

4 catalyst supply pipe

5 transportation pipe for the esterification reaction product

6 melt polycondensation reactor (first stage)

7 melt polycondensation reactor (second stage)

8 melt polycondensation reactor (third stage)

BEST MODE FOR CARRYING OUT THE INVENTION Monomer Components Constitutingthe Resin

The polyester resin in the present invention is one produced bypolycondensing a dicarboxylic acid component containing an aromaticdicarboxylic acid or its ester-forming derivative as the main componentand a diol component containing ethylene glycol as the main component inthe presence of at least an antimony compound and a phosphorus compound,via an esterification reaction or an ester exchange reaction.

In the present invention, specifically, the aromatic dicarboxylic acidor its ester-forming derivative may, for example, be terephthalic acid,phthalic acid, isophthalic acid, dibromoisophthalic acid, sodiumsulfoisophthalate, phenylenedioxy dicarboxylic acid,4,4′-diphenyldicarboxylic acid, 4,4′-diphenyl ether dicarboxylic acid,4,4′-diphenyl ketone dicarboxylic acid, 4,4′-diphenoxy ethanedicarboxylic acid, 4,4′-diphenyl sulfone dicarboxylic acid,2,6-naphthalene dicarboxylic acid as well as a C₁₋₄ alkyl ester of suchan aromatic dicarboxylic acid, such as dimethyl terephthalate ordimethyl 2,6-naphthalene dicarboxylate, and a halogenated productthereof. Among them, terephthalic acid, 2,6-naphthalene dicarboxylicacid or an alkyl ester thereof, is preferred, and terephthalic acid isparticularly preferred.

Further, the dicarboxylic acid component other than the above aromaticdicarboxylic acid and its ester-forming derivative, may, for example, bean alicyclic dicarboxylic acid such as hexahydroterephthalic acid orhexahydroisophthalic acid, and an aliphatic dicarboxylic acid such assuccinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid,azelaic acid, sebacic acid, undecadicarboxylic acid ordodecadicarboxylic acid, as well as a C₁₋₄ alkyl ester of such analicyclic dicarboxylic acid or an aliphatic dicarboxylic acid, and ahalogenated product thereof.

Further, the diol component other than ethylene glycol, may, forexample, be an aliphatic diol such as trimethylene glycol,tetramethylene glycol, pentamethylene glycol, hexamethylene glycol,octamethylene glycol, decamethylene glycol, neopentyl glycol,2-ethyl-2-butyl-1,3-propane diol, diethylene glycol, polyethylene glycolor polyltetramethylene ether glycol, an alicyclic diol such as1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,1-cyclohexanedimethylol,1,4-cyclohexanedimethylol or 2,5-norbornanedimethylol, and an aromaticdiol such as xylene glycol, 4,4′-dihydroxybiphenyl,2,2-bis(4′-hydroxyphenyl)propane,2,2-bis(4′-β-hydroxyethoxyphenyl)propane, bis(4-hydroxyphenyl)sulfone orbis(4-β-hydroxyethoxyphenyl)sulfonic acid, as well as an ethylene oxideadduct or a propylene oxide adduct, of 2,2-bis(4′-hydroxyphenyl)propane.

Further, one or more of a hydroxycarboxylic acid and an alkoxycarboxylicacid, such as glycolic acid, p-hydroxybenzoic acid and p-β-hydroxyethoxybenzoic acid, a single functional component such as stearyl alcohol,benzyl alcohol, stearic acid, benzoic acid, t-butyl benzoic acid andbenzoyl benzoic acid, and a polyfunctional component with at leasttrifunctional, such as tricarbarylic acid, trimellitic acid, trimesicacid, pyromellitic acid, gallic acid, trimethylolethane,trimethylolpropane, glycerol and pentaerythritol, may be used ascopolymerizable components.

Particularly from the viewpoint of further suppressing the elution ofantimony, the polyester resin of the present invention is one producedby polycondensing a dicarboxylic acid component containing the abovearomatic dicarboxylic acid or its ester-forming derivative in an amountof at least 50 mol %, preferably at least 90 mol %, more preferably atleast 95 mol %, particularly preferably at least 99 mol %, of thedicarboxylic acid component, and a diol component containing ethyleneglycol in an amount of at least 50 mol %, preferably at least 90 mol %,further preferably at least 95 mol %, particularly preferably at least97 mol %, of the diol component, via an esterification reaction or anester exchange reaction. Here, the polyester resin may have diethyleneglycol formed as a by-product in the reaction system, copolymerized, andthe content of diethylene glycol inclusive of one added as acopolymerizable component from outside the system, is preferably notmore than 5 mol %. If the content of diethylene glycol is large, thedegree of suppressing the elusion of antimony as the polyester resintends to be low, and further, the melt heat stability, heat resistance,mechanical strength, etc. as a resin tend to deteriorate.

Antimony and Phosphorus

In the present invention, the polycondensation is carried out in thepresence of at least an antimony compound and a phosphorus compound, andaccordingly, in the polyester resin of the present invention, at leastan antimony component and a phosphorus component will be contained.

Here, specifically, the antimony compound may, for example, be antimonytrioxide, antimony pentoxide, antimony acetate, methoxy antimony,triphenyl antimony or antimony glycolate. Among them, antimony trioxideis preferred.

Further, specifically, the phosphorus compound may, for example, be apentavalent phosphorus compound such as orthophosphoric acid,polyphosphoric acid and esters thereof, such as trimethyl phosphate,triethyl phosphate, tri-n-butyl phosphate, trioctyl phosphate, triphenylphosphate, tricresyl phosphate, tris(triethylene glycol)phosphate,ethyldiethyl phosphonoacetate, methyl acid phosphate, ethyl acidphosphate, isopropyl acid phosphate, butyl acid phosphate, monobutylphosphate, dibutyl phosphate, dioctyl phosphate and triethylene glycolacid phosphate, or a trivalent phosphorus compound such ashypophosphorous acid, phosphorous acid and esters thereof, such asdimethyl phosphite, diethyl phosphite, trimethyl phosphite, triethylphosphite, tributyl phosphite, trisdodecyl phosphite, trisnonyldecylphosphite, diphenyl phosphite and triphenyl phosphite as well as a metalsalt such as a lithium, sodium or potassium salt, thereof.

Among them, from the viewpoint of further suppressing elution ofantimony, a pentavalent phosphorus compound such as an ester oforthophosphoric acid, such as ethyl acid phosphate, or a trivalentphosphorus compound such as hypophosphorous acid, phosphorous acid or anester of phosphorous acid, such as diethyl phosphite, trimethylphosphite or triethyl phosphite, is preferred, and a trivalentphosphorus compound such as phosphorous acid or an ester of phosphorousacid, is particularly preferred.

In the present invention, the amount of the above antimony compound andthe above phosphorus compound used for the polycondensation and theresulting respective contents in the polyester resin are such that fromthe viewpoint of further suppressing elution of antimony, the content asantimony atoms (Sb) of the antimony component in the polyester resin ispreferably from 10 to 250 weight ppm, more preferably from 30 to 150weight ppm, particularly preferably from 50 to 110 weight ppm. If thecontent as antimony atoms is less than the above range, thepolymerizability tends to be inadequate, whereby the productivity tendsto deteriorate, and the color tone also tends to deteriorate, andby-products also tend to increase. On the other hand, if it exceeds theabove range, it tends to be difficult to suppress the amount of elution.

Further, the content as phosphorus atoms (P) of the phosphorus componentin the polyester resin is preferably relatively small at a level of from0.1 to 20 weight ppm, more preferably from 1.0 to 15 weight ppm,particularly preferably from 2.0 to 10 weight ppm, from the viewpoint offurther suppressing elution of antimony. If the content as phosphorusatoms is less than the above range, the color tone tends to deteriorate,and by-products also tend to increase. On the other hand, if it exceedsthe above range, it tends to be difficult to control the amount ofelution.

Further, the ratio (Sb/P) of the content (weight ppm) as antimony atoms(Sb) of the antimony component to the content (weight ppm) as phosphorusatoms (P) of the phosphorus component in the polyester resin, ispreferably from 6.0 to 30, more preferably from 8 to 20, particularlypreferably from 9 to 15, from the viewpoint of suppressing elution ofantimony. If the ratio of the content as antimony atoms to the contentas phosphorus atoms, is less than the above range, thepolycondensability tends to be inadequate, whereby the productivitytends to deteriorate, the color tone also tends to deteriorate, andby-products also tend to increase. On the other hand, if it exceeds theabove range, it tends to be difficult to control the amount of elution.

Other Constituting Element Components

Further, from the viewpoint of further suppressing elution of antimony,the polyester resin of the present invention is preferably one which ispolycondensed in the coexistence of a compound of at least one metalelement selected from the group consisting of Groups IA and IIA of theperiodic table, zinc, aluminum, gallium, germanium, titanium, zirconium,hafnium, manganese, iron and cobalt. Accordingly, the polyester resin ofthe present invention preferably contains at least one metal elementcomponent selected from the group consisting of Groups IA and IIA of theperiodic table, zinc, aluminum, gallium, germanium, titanium, zirconium,hafnium, manganese, iron and cobalt. And, in the present invention, fromthe viewpoint of further suppressing elution of antimony, the totalamount of these metal compounds used at the time of the polycondensationand accordingly the total content thereof in the polyester resin arepreferably such that the total content as metal atoms (M) of such metalelement components in the polyester resin, is preferably from 0.1 to 100weight ppm, more preferably from 1 to 30 weight ppm.

The above coexistent compound may, for example, be an oxide, hydroxide,alkoxide, carboxylate, carbonate, oxalate and halide of lithium, sodiumor potassium of Group IA of the periodic table, beryllium, magnesium,calcium, strontium or barium of Group IIA of the periodic table, zinc,aluminum, gallium, germanium, titanium, zirconium, hafnium, manganese,iron and cobalt.

Among such coexistent compound, in the present invention, a metalcompound of Group IA or IIA of the periodic table, particularly amagnesium compound, is preferred. Specifically, such a magnesiumcompound may, for example, be magnesium oxide, magnesium hydroxide,magnesium alkoxide, magnesium acetate or magnesium carbonate, and amongthem, magnesium acetate is preferred.

Further, the amount of the magnesium compound used for thepolycondensation and the resulting content in the polyester resin aresuch that from the viewpoint of further suppressing elution of antimony,the content as magnesium atoms (Mg) of the magnesium component in thepolyester resin, is preferably from 0.1 to 30 weight ppm, morepreferably from 1.0 to 20 weight ppm, particularly preferably from 3.0to 15 weight ppm. If the content as magnesium atoms is less than theabove range, it tends to be difficult to suppress the amount of elution.On the other hand, if it exceeds the above range, the color tone tendsto deteriorate, and by-products also tend to increase.

Further, in a case where the coexistent metal compound is a magnesiumcompound, from the viewpoint of further suppressing elution of antimony,the ratio (Mg/P) of the content (weight ppm) as magnesium atoms (Mg) ofthe magnesium component to the content (weight ppm) as phosphorus atoms(P) of the phosphorus component in the polyester resin, is preferablyfrom 1.1 to 3.0, more preferably from 1.3 to 2.5 weight ppm,particularly preferably from 1.5 to 2.0. If the ratio of the content asmagnesium atoms to the content as phosphorus atoms, is less than theabove range, it tends to be difficult to suppress the amount of elution.On the other hand, if it exceeds the above range, the color tone tendsto deteriorate, and by-products also tend to increase.

Further, from the viewpoint of further suppressing elution of antimony,among these coexistent metal compounds, a titanium compound is alsopreferred, and particularly a combined use with a metal compound ofGroup IA or IIA of the periodic table, particularly with the abovemagnesium compound of Group IIA of the periodic table, is preferred.Specifically, such a titanium compound may, for example, betetra-n-propyl titanate, tetra-i-propyl titanate, tetra-n-butyltitanate, tetra-n-butyl titanate-tetramer, tetra-t-butyl titanate,tetracyclohexyl titanate, tetraphenyl titanate, tetrabenzyl titanate,titanium acetate, titanium oxalate, titanium acetyl acetonate, potassiumtitanium oxalate, sodium titanium oxalate, potassium titanate, sodiumtitanate, a titanic acid/aluminum hydroxide mixture, titanium chloride,a titanium chloride/aluminum chloride mixture, titanium bromide,titanium fluoride, potassium hexafluoro titanate, cobalt hexafluorotitanate, manganese hexafluoro titanate, ammonium hexafluoro titanate ortitanium acetyl acetonate. Among them, tetra-n-propyl titanate,tetra-i-propyl titanate, tetra-n-butyl titanate, titanium oxalate orpotassium titanium oxalate, is preferred.

Further, the amount of the titanium compound used at the time of thepolycondensation and the resulting content in the polyester resin aresuch that from the viewpoint of further suppressing elution of antimony,the content as titanium atoms (Ti) of the titanium component in thepolyester resin, is preferably from 0.25 to 10 weight ppm, morepreferably from 0.75 to 5.0 weight ppm, particularly preferably from 1.5to 4.0 weight ppm. If the content as titanium atoms is less than theabove range, the degree of suppressing the amount of elution tends to below. On the other hand, if it exceeds the above range, the color tonetends to deteriorate, and by-products also tend to increase.

Further, typically, other coexistent metal compounds may, for example,be a compound of metal of Group IA of the periodic table, such aslithium acetate, sodium acetate or potassium acetate, a compound of ametal of Group IIA of the periodic table, such as calcium oxide, calciumhydroxide, calcium acetate or calcium carbonate, a zinc compound such aszinc acetate, zinc benzoate, zinc methoxide, zinc acetyl acetonate orzinc chloride, a germanium compound such as germanium dioxide, germaniumtetraoxide, germanium hydroxide, germanium tetraethoxide, germaniumtetra butoxide or germanium oxalate, a manganese compound such asmanganese oxide, manganese hydroxide, manganese methoxide, manganeseacetate, manganese benzoate, manganese acetyl acetonate or manganesechloride, or a cobalt compound such as cobalt formate, cobalt acetate,cobalt stearate, cobalt naphthenate, cobalt benzoate, cobalt acetylacetonate, cobalt carbonate, cobalt oxalate, cobalt chloride or cobaltbromide.

Physical Properties of the Polyester Resin

The polyester resin of the present invention is one whereby the amountof antimony eluted when immersed in a hot water of 95° C. for 60 minutesin the form of particles having a number average particle weight of 24mg, is not more than 1 μg more preferably not more than 0.5 μg, furtherpreferably not more than 0.2 μg, particularly preferably not more than0.1 μg, per 1 g of the polyester resin, as antimony atoms (Sb).

Here, the amount of elution as antimony atoms (Sb) is one obtained byheating 50 g of the polyester resin particles having a number average ofparticle weight of 24 mg at 120° C. for 10 hours for crystallization,followed by immersion in 150 g of hot water of 95° C. for 60 minutes,measuring the antimony extracted in water at that time, as antimony atomconcentration C (ppb) by an induction coupled plasma mass spectrometryand calculating the eluted amount D (μg) as antimony atoms per 1 g ofthe polyester resin, by the following formula.

D(μg)=(C/10⁹)×(150/50)×10⁶

Further, from the viewpoint of the taste deterioration resistance of thecontained beverage when used as e.g. a bottle, the polyester resin ofthe present invention is preferably such that the difference(ΔAA=AA_(s)−AA_(o)) between the acetaldehyde content (AA_(s); ppm) in amolded product when injection-molded at 280° C. and the acetaldehydecontent (AA_(o); ppm) before the injection molding, is not more than 20ppm, more preferably not more than 15 ppm.

Further, from the viewpoint of suppressing elution of antimony, thepolyester resin of the present invention preferably has an intrinsicviscosity [η] (the value measured at 30° C. in a solution of a mixedsolvent of phenol/tetrachloroethane (weight ratio: 1/1)) of usually from0.35 to 0.75 dl/g in the case of a melt polycondensed resin, and, in thecase of a solid phase polycondensed resin, preferably of from 0.70 to1.0 dl/g, more preferably from 0.70 to 0.90 dl/g, particularlypreferably from 0.70 to 0.80 dl/g. Further, as the color tone, colorcoordinate b of Hunter's color difference formula in the Lab colorsystem as disclosed in Reference 1 of JIS Z8730, is preferably not morethan 3, particularly preferably from −5 to 2. Further, the content ofacetaldehyde is preferably not more than 5 ppm, particularly preferablynot more than 3 ppm.

Further, in the present invention, the polyester resin may furthercontain an antioxidant, a ultraviolet absorber, a photostabilizer, anantistatic agent, a lubricant, a blocking preventive agent, anantifogging agent, a nucleating agent, a plasticizer, a colorant, afiller, etc.

Further, the polyester resin of the present invention is characterizedin that the haze in a thickness of 5 mm of a molded product afterinjection molding at 270° C. is not more than 50% (the above polyester{circle around (5)}), preferably not more than 30%, more preferably notmore than 20%, particularly preferably not more than 10%. If this hazeexceeds the above range, the transparency as molded into a bottle at alow temperature, tends to be poor, and accordingly, the molding isobliged to be carry out at a high temperature, whereby it will beimpossible to adequately suppress formation of acetaldehyde orcontamination of the mold during the molding.

Further, the polyester resin of the present invention is such that thedifference (ΔAA=AA_(s)−AA_(o)) between the acetaldehyde content (AA_(s);ppm) of the resin in a molded product after injection molding at 270° C.and the acetaldehyde content (AA_(o); ppm) of the resin before theinjection molding, is preferably not more than 15 ppm, more preferablynot more than 13 ppm, particularly preferably not more than 10 ppm. Ifthis value ΔAA exceeds the above range, a problem is likely to resultsuch that the taste of the contained beverage will be impaired when usedas a container for a beverage as a molded product such as a bottle.

Further, the polyester resin of the present invention is such that thedifference (ACT=CT_(s)−CT_(o)) between the cyclic trimer content(CT_(s); wt %) of the resin in a molded product after injection moldingat 270° C. and the cyclic trimer content (CT_(o); wt %) of the resinbefore the injection molding, is preferably not more than 0.05 wt %,more preferably not more than 0.03 wt %, particularly preferably notmore than 0.01 wt %. If this value ΔCT exceeds the above range,contamination of the mold tends to result at the time of molding into abottle or the like.

Production Process

The polyester resin of the present invention is produced bypolycondensing a dicarboxylic acid component containing an aromaticdicarboxylic acid or its ester-forming derivative as the main componentand a diol component containing ethylene glycol as the main component inthe presence of at least an antimony compound and a phosphorus compound,preferably in the coexistence of the above-mentioned metal compound,particularly the magnesium compound and/or the titanium compound, via anesterification reaction or an ester exchange reaction, but basically inaccordance with a common process for producing a polyester resin.Namely, it is produced by introducing into a slurry preparation tank theabove dicarboxylic acid component containing an aromatic dicarboxylicacid or its ester-forming derivative as the main component and the diolcomponent containing ethylene glycol as the main component together withan optional copolymer component, etc., followed by mixing with stirringto obtain a raw material slurry, subjecting it to an esterificationreaction in an esterification reactor under atmospheric pressure orelevated pressure under heating or to an ester exchange reaction in thepresence of an ester exchange catalyst, then transferring the obtainedpolyester low molecular weight product as the esterification reactionproduct or the ester exchange reaction product to a polycondensationtank, and melt polycondensing it in the presence of the above compoundsunder atmospheric pressure or gradually reduced pressure under heating.

As a process whereby the polyester resin of the present invention can beobtained, there may be mentioned a process wherein atoms of antimony,phosphorus, etc., are added in specific ranges at specific ratios to thepolyester resin obtainable. Accordingly, the present invention alsorelates to such a process for producing a polyester resin.

Namely, as a preferred process for producing the polyester resin of thepresent invention, a process for producing a polyester resin may bementioned which comprises polycondensing a dicarboxylic acid componentcontaining an aromatic dicarboxylic acid or its ester-forming derivativeas the main component and a diol component containing ethylene glycol asthe main component, characterized in that a catalyst is added to thereaction system so that the following respective atoms derived from thecatalyst will be contained in the following concentration ranges basedon the obtainable polyester resin:

0<T≦50 ppm

0≦Sb≦250 ppm

0.1≦P≦200 ppm

6.0≦Sb/P≧30

(in the above formulae, T is the total concentration (ppm) of at leastone type of atoms selected from the group consisting of titanium atoms,hafnium atoms and zirconium atoms in the resin, Sb is the concentration(ppm) of antimony atoms in the resin, and P is the concentration (ppm)of phosphorus atoms in the resin).

Further, preferred ranges of the dicarboxylic acid component, the diolcomponent, T, Sb, P, etc., in such production process are the same asdescribed above with respect to the components of the polyester resin ofthe present invention.

Further, in the above process for producing a polyester resin of thepresent invention, preferably, in addition to the above-mentionedpolymerization catalyst, the following polymerization catalyst isfurther added to the reaction system so that the following respectiveatoms derived from the catalyst will be contained within the followingconcentration ranges based on the obtainable polyester resin:

0.1≦M≦200 ppm

1.1≦M/P≦15

(M is the total content (ppm) of at least one type of metal atomsselected from the group consisting of Group IA metal atoms, Group IIAmetal atoms, manganese atoms, iron atoms and cobalt atoms in the resin).

In the production process, preferred ranges of M, P, etc., are the sameas described above with respect to the components for the polyesterresin of the present invention.

More preferably, at a stage where the esterification ratio is less than90%, a phosphorus compound is added to the reaction mixture containingthe esterification reaction product, and after the esterification ratiohas reached at least 90%, at least one metal atom compound selected fromthe group consisting of a Group IA element compound, a Group IIA elementcompound, a manganese compound, an iron compound and a cobalt compound,is added, and thereafter, at least one compound selected from the groupconsisting of a titanium compound, a zirconium compound, a hafniumcompound, an aluminum compound, a zinc compound, a gallium compound anda germanium compound, is added.

In the foregoing, details of preferred compounds and the order of theiraddition, are as disclosed in Disclosure of the Invention for everypreferred embodiment of the polyester resin of the present invention asdescribed hereinafter.

Further, in the case of the ester exchange reaction, it is necessary toemploy an ester exchange catalyst, and it is necessary to employ such anester exchange catalyst in a large amount. Accordingly, in the presentinvention, one produced via an esterification reaction, is preferred.

Here, in the case of the esterification reaction, preparation of the rawmaterial slurry is carried out by mixing the dicarboxylic acid componentcontaining an aromatic dicarboxylic acid as the main component and thediol component containing ethylene glycol as the main component, and anoptional copolymerizable component, etc., so that the molar ratio of thediol component to the dicarboxylic acid component will be preferablywithin a range of from 1.02 to 2.0, more preferably from 1.03 to 1.7. Ifthe molar ratio is less than the above range, the esterificationreactivity tends to be low. On the other hand, if it exceeds the aboverange, the amount of formation of diethylene glycol tends to increase.

Further, the esterification reaction is carried out usually by means ofa multi stage reaction apparatus having a plurality of esterificationreactors connected in series under reflux of ethylene glycol, whileremoving water formed by the reaction and excess ethylene glycol out ofthe system, until the esterification ratio (the proportion of theesterified by a reaction with the diol component among the totalcarboxyl groups of the raw material dicarboxylic acid component) reachesusually at least 90%, preferably at least 93%. Further, the numberaverage molecular weight of the polyester low molecular weight productas the obtainable esterification reaction product, is preferably from500 to 5,000.

With respect to the reaction conditions in the esterification reaction,the reaction temperature in the esterification reactor for the firststage is usually from 240 to 270° C., preferably from 245 to 265° C.,the relative pressure to the atmospheric pressure is usually from 5 to300 kPa (from 0.05 to 3 kg/cm²G), preferably from 10 to 200 kPa (from0.1 to 2 kg/cm²G), the reaction temperature at the final stage isusually from 250 to 280° C., preferably from 255 to 275° C., and therelative pressure to the atmospheric pressure is usually from 0 to 150kPa (from 0 to 1.5 kg/cm²G), preferably from 0 to 130 kPa (from 0 to 1.3kg/cm²G). Further, in a case where the reaction is carried out in asingle esterification reactor, the reaction conditions at the finalstage will be employed.

Further, in the esterification reaction, it is possible to suppress theside reaction to form diethylene glycol from ethylene glycol, by addinga small amount of a tertiary amine such as triethylamine, tributylamineor benzyldimethylamine, a quaternary ammonium hydroxide such astetraethylammonium hydroxide, tetrabutylammonium hydroxide ortrimethylbenzylammonium hydroxide, or a basic compound such as lithiumcarbonate, sodium carbonate, potassium carbonate or sodium acetate.

Further, melt polycondensation is carried out usually by means of amulti stage reaction apparatus having a plurality of meltpolycondensation tanks connected in series, under reduced pressure whiledistilling off formed ethylene glycol out of the system. The reactionapparatus may, for example, be one comprising a perfect mixing typereactor equipped with stirring vanes for the first stage and horizontalplug flow type reactors equipped with stirring vanes for the second andthird stages.

With respect to the reaction conditions in the melt polycondensation,the reaction temperature in the polycondensation tank for the firststage is usually from 250 to 290° C., preferably from 260 to 280° C. andthe absolute pressure is usually from 65 to 1.3 kPa (from 500 to 10Torr), preferably from 26 to 2 kPa (from 200 to 15 Torr), and thereaction temperature at the final stage is usually from 265 to 300° C.,preferably from 270 to 295° C., and the absolute pressure is usuallyfrom 1.3 to 0.013 kPa (from 10 to 0.1 Torr), preferably from 0.65 to0.065 kPa (from 5 to 0.5 Torr). The reaction conditions for anintermediate stage are selected to be intermediate conditions thereof,and for example, in a three stage reaction apparatus, the reactiontemperature in the second stage is usually from 265 to 295° C.,preferably from 270 to 285° C., and the absolute pressure is usuallyfrom 6.5 to 0.13 kPa (from 50 to 1 Torr), preferably from 4 to 0.26 kPa(from 30 to 2 Torr).

Further, in the polycondensation, the addition of the above antimonycompound, the above phosphorus compound and the above coexistent metalcompound, etc. to the reaction system, may be at an optional stage of astep of preparing a slurry of the starting material dicarboxylic acidcomponent and the diol component or a step of the esterificationreaction, or at an initial stage in the melt polycondensation step.However, in order to further suppress elution of antimony in theobtainable polyester resin and obtain the effect for reducing by-productsuch as acetaldehyde effectively, in addition to sufficientpolymerization activities, the above-mentioned phosphorus compound ispreferably added to a slurry preparation tank or an esterificationreaction tank for the first stage, particularly preferably to the slurrypreparation tank. Further, the above antimony compound and the abovecoexistent metal compounds are preferably added to the esterificationreaction product having an esterification ratio of at least 90% in theesterification reaction step, specifically, for example, to theesterification reaction tank for the final stage in the multi stagereaction apparatus or to a stage of transporting the esterificationreaction product to the melt polycondensation step, and it isparticularly preferred that the above antimony compound and a metalcompound of Group IA or IIA of the periodic table among the abovecoexistent metal compounds, are added before the addition of a compoundof zinc, aluminum, gallium, germanium, titanium, zirconium or hafniumamong the above-mentioned coexistent metal compounds.

The resin obtained by the above melt polycondensation is usuallywithdrawn in the form of a strand from a discharge outlet provided atthe bottom portion of the polycondensation tank and, while being cooledby water or after being cooled with water, cut by a cutter intoparticles such as pellets or chips. Further, such particles after themelt polycondensation, are subjected to solid phase polycondensation byheating them at a temperature of usually 190 to 230° C., preferably from195 to 225° C. in an inert gas atmosphere such as nitrogen, carbondioxide or argon, under a pressure of usually at most 100 kPa (1kg/cm²G), preferably at most 20 kPa (0.2 kg/cm²G) as a relative pressureto the atmospheric pressure, or under a reduced pressure of usually from6.5 to 0.013 kPa (from 50 to 0.1 Torr), preferably from 1.3 to 0.065 kPa(from 10 to 0.5 Torr), as the absolute pressure. By this solid phasepolycondensation, it is possible to further increase the polymerizationdegree and to reduce by-products such as acetaldehyde.

At that time, prior to the solid phase polycondensation, it is preferredto heat the resin particles in an inert gas atmosphere, or in a steamatmosphere or a steam-containing inert gas atmosphere usually from 120to 200° C., preferably from 130 to 190° C. to crystallize the surface ofthe resin particles.

Further, it is possible to deactivate the catalyst used forpolycondensation by subjecting the resin obtained by the above meltpolycondensation or solid phase polycondensation to water treatment ofdipping them in warm water of at least 40° C. for at least 10 minutes,or steam treatment of contacting them with steam or a steam-containinggas of at least 60° C. for at least 30 minutes, or treatment with anorganic solvent, or treatment with an aqueous acidic solution of e.g.various mineral acids, organic acids or phosphoric acid, or treatmentwith an organic solvent solution or an aqueous alkaline solution of e.g.an amine or a metal of Group IA or IIA.

Use of the Polyester Resin

The polyester resin of the present invention may, for example, be moldedinto a preform by injection molding, followed by stretch blow molding,or may be molded into a parison by extrusion, followed by blow molding,to form a bottle or the like, or may be molded into a sheet byextrusion, followed by hot forming to form a tray, a container or thelike, or such a sheet may be biaxially stretched into a film or thelike, or formed in a fiber shape to obtain various fiber products, inaccordance with usual methods.

Preferred Embodiment as a Bottle for a Non-carbonated Beverage

The polyester resin on the present invention is preferably the abovepolyester {circle around (2)} for the purpose of obtaining a containerhaving excellent transparency, heat resistance and strength with aproductivity higher than ever while suppressing elution of antimony,particularly when molded into a hollow container for a non-carbonatedbeverage such as mineral water, tea or juice. Such a preferredembodiment will be described in detail.

Monomer Components Constituting the Resin

The ethylene glycol component in the polyester resin is preferably atleast 96 mol %, more preferably at least 97.5 mol %, based on the totalglycol component in the resin; the diethylene glycol component in theresin is preferably not more than 2.5 mol % of the total glycolcomponent; and the terephthalic acid component is preferably at least98.5 mol %, more preferably at least 99.0 mol %, of the total acidcomponent. With respect to the diethylene glycol component, diethyleneglycol formed by a side reaction in the reaction system may becopolymerized, and the content of the dioxyterephthalate componentinclusive of one added as a copolymerizable component from outside thesystem, is preferably not more than 2.5 mol %, more preferably from 1.0mol % to 2.5 mol %, further preferably from 1.8 mol % to 2.3 mol %, ofthe total glycol component. If the amount of the copolymerizablecomponent exceeds the above range, it tends to be difficult to obtain amolded product having adequate heat resistance and strength efficiently,and by-products such as acetaldehyde in the resin tend to increase, thethermal stability at the time of molding tends to deteriorate, or whenformed into a molded product, the acetaldehyde content in the moldedproduct tends to increase. Further, if the amount of the copolymerizablecomponent is less than the above range, the transparency tends todeteriorate, when formed into a molded product.

Antimony and Phosphorus

The amount of the antimony compound to be used is preferably such anamount that the content as antimony atoms (Sb) will be from 10 to 250ppm more preferably from 30 to 180 ppm, further preferably from 60 to120 ppm, particularly preferably from 80 to 100 ppm, based on thetheoretical yield of the polyester resin. If the amount of antimonyatoms is small, the polymerizability tends to be inadequate, whereby theproductivity tends to be poor, the color tone also tends to deteriorate,and the amount of by-products such as acetaldehyde also tends toincrease. If the amount of antimony atoms is large, the transparencytends to deteriorate when formed into a molded product, and the amountof by-products such as acetaldehyde tends to increase, or the color tonetends to deteriorate.

Further, the content of phosphorus atoms in the polyester resin is thesame as mentioned above, but for a non-carbonated beverage bottle, it ismore preferably not more than 14 ppm, particularly preferably from 5 to10 ppm.

If the amount of phosphorus atoms is large, the heat resistance tends todeteriorate when formed into a molded product.

Further, the ratio of antimony atoms Sb (ppm) to the content P (ppm) ofphosphorus atoms in the obtainable polyester resin, is as mentionedabove. When the Sb/P range is within the above range, the balance of thepolymerization speed, the color tone, the amount of by-products such asacetaldehyde, and heat resistance and transparency, etc., when formedinto a molded product, are good.

Other Constituting Element Components

Further, the polycondensation is preferably carried out in the presenceof any one or a plurality of metal element compounds selected from acompound of Group IA element of the periodic table except hydrogen, acompound of Group IIA element, a manganese compound, an iron compound, acobalt compound, a titanium compound, a zirconium compound, a hafniumcompound, an aluminum compound, a zinc compound, a gallium compound anda germanium compound, in addition to the antimony compound and thephosphorus compound. The resin of the present invention preferablycontains metals (M) derived from them.

Compounds of these metal elements have effects for improvement of thepolymerization rate or effects for improving the color tone of theobtainable polyester or reducing the amount of by-products such asacetaldehyde. However, if they are present too much, the color tone,by-products such as acetaldehyde, or heat resistance when formed into amolded product, tend to be adversely affected.

Accordingly, the content of these metal compounds in the polyester resinis preferably from 0.1 to 100 ppm, and in a case where a magnesiumcompound is used, the weight ratio of the content of magnesium atoms tothe content of phosphorus atoms, is preferably from 1.1 to 3.0, morepreferably from 1.5 to 2.0. Further, its content is preferably from 3 to25 ppm, more preferably from 8 to 18 ppm, based on the obtainablepolyester resin, as magnesium atoms.

Further, in a case where a titanium compound is used, its content ispreferably from 0.25 to 10 ppm, more preferably from 0.75 to 4 ppm as atitanium element based on the obtainable polyester resin.

Physical Properties of Polyester {circle around (2)}

Further, the intrinsic viscosity IV is from 0.65 to 0.90 (dl/g),preferably from 0.70 to 0.80 dl/g. If the intrinsic viscosity is low,the strength or transparency tends to deteriorate when formed into amolded product such as a bottle, and if the intrinsic viscosity is high,it tends to be difficult to obtain a molded product having adequate heatresistance and strength efficiently, and the productivity of the resinand the productivity at the time of molding tend to be poor, and theamount of by-products such as acetaldehyde in the molded product tendsto increase.

Further, the temperature-lowering crystallization temperature Tc2 of theresin is from 150 to 200° C., preferably from 160 to 190° C. In thiscase, for the temperature-lowering crystallization temperature, theresin is injection-molded to form a stepped molded plate of the shapeshown in FIG. 1, having a size of 50 mm×100 mm and a thicknesstransversely stepped six stages from 6 mm to 3.5 mm with each step being0.5 mm, and the forward portion (portion A in FIG. 1) of 3.5 mm inthickness of the molded plate is heated from 20° C. to 285° C. at a rateof 20° C./min in a nitrogen stream by means of a differential scanningcalorimeter, maintained in a molten state at 285° C. for 5 minutes andthen cooled to 20° C. at a rate of 10° C./min, whereby thetemperature-lowering crystallization temperature is the crystallizationpeak temperature observed during the temperature drop (details will bedescribed hereinafter).

If the temperature-lowering crystallization temperature is higher thanthe above range, the transparency tends to be poor when formed into amolded product, and if it is lower than the above range, the releaseproperty at the time of molding tends to be poor.

Further, the acetaldehyde content in the resin is usually not more than10 ppm, preferably not more than 3 ppm, more preferably not more than 2ppm, further preferably not more than 1 ppm. If the acetaldehyde contentis high, when formed into a bottle for a beverage or the like, the tasteof the content tends to deteriorate.

Further, the carboxylic acid terminal amount of the resin is usuallyfrom 1 to 50 equivalents/ton resin, preferably from 1 to 40equivalents/ton resin. If the carboxylic acid terminal amount is large,the heat stability during the molding tends to deteriorate, and theamount of by-products such as acetaldehyde tends to increase when formedinto a molded product. Here, the carboxylic acid terminal amount ismeasured by the method disclosed in Examples relating to polyester{circle around (2)} in the Examples given hereinafter.

Further, the color coordinate value b in the Hunter's color differenceformula of the resin is preferably at most 4, more preferably at most 2.If the color coordinate value b exceeds the above range, the resin tendsto be yellow-colored, which impairs the appearance of a molded productsuch as a bottle or the like.

Production Process

In the case of the foregoing embodiment for a hollow container for anon-carbonated beverage, the process for producing a polyester resin,whereby a container having excellent transparency, heat resistance andstrength can be obtained with a productivity higher than ever, whilesuppressing elution of antimony, is particularly preferably thefollowing embodiment, in addition to the above-described process forproducing a polyester, whereby elution of antimony is suppressed.

Firstly, the polyester resin of this embodiment can be produced by aprocess which comprises preparation of a raw material slurry, anesterification method or an ester exchange method and meltpolymerization, in accordance with a conventional process. However, in acase where an ester exchange reaction is carried out by using aterephthalic acid ester as the raw material, an ester exchange catalystsuch as a titanium compound, a magnesium compound, a calcium compound ora manganese compound, is usually required. And, there may be a casewhere the amount of the ester exchange catalyst required is too much toobtain a polyester resin of the present invention. Accordingly, it ispreferred to carry out esterification by using terephthalic acid as adicarboxylic acid component.

The esterification reaction may be carried out by means of theterephthalic acid component and the ethylene glycol component only.However, it can be carried out in the presence of various additives. Forexample, an antimony compound as a catalyst for polycondensation, or acompound of a Group IA element except for hydrogen, a compound of aGroup IIA, a phosphorus compound, etc. to be contained in the polyesterresin, may be added to the esterification reaction step. Further, it ispreferred to carry out the reaction by adding a small amount of a basiccompound in the same manner as the above-mentioned process.

The phosphorus compound is preferably mixed to the esterificationreaction product at a stage where the esterification ratio is less than90%. For example, in a case where a multi stage reaction apparatus isemployed, it is added to the slurry preparation tank or to the firststage of esterification, and it is preferably added to the slurrypreparation tank. The compound of a Group IA element except for hydrogenand/or the compound of a Group IIA element, is added to the esterifiedproduct preferably at a stage where the esterification ratio is at least90%. For example, in a case where the multi stage reaction apparatus isto be used, it will be added at the second stage of esterification.

Although the reason is not necessarily clearly understood, by this orderof addition, not only the amount of by-production of diethylene glycolunits will be suppressed, but also precipitation of solid foreignmatters will be suppressed, the polymerizability will be good, and thethermal decomposition reactions will be suppressed, so that in theresulting resin, the carboxylic acid terminal number or the amount ofby-products such as acetaldehyde can be suppressed to a low level.

The antimony compound is added preferably to a reacted product having anesterification ratio of at least 90%. Specifically, it is suppliedpreferably to a later stage of the esterification step at which theesterification ratio reaches to the prescribed level or to anesterification reaction product during the transportation from theesterification step to the melt polycondensation reaction step,particularly preferably to the esterification reaction product duringthe transportation from the esterification step to the meltpolycondensation reaction step. By the addition at this position, notonly the amount of by-production of diethylene glycol units will besuppressed, but also precipitation of solid foreign matters will besuppressed, the polymerizability will be good, and thermal decompositionreactions will be suppressed, whereby in the obtainable resin, thecarboxylic acid terminal number or the amount of by-products such asacetaldehyde can be suppressed to a low level.

The titanium compound, the zirconium compound, the hafnium compound, thealuminum compound, the zinc compound, the gallium compound or thegermanium compound is supplied preferably to the esterification step orto the esterification reaction product supplied to the meltpolycondensation reaction step, and more preferably it is added to areaction product at a later stage of the esterification reaction atwhich the esterification ratio is at least 90%. It is added preferablyat a later step than the addition of the compound of Group IA elementexcept for hydrogen and/or the compound of Group IIA element.Specifically, it is supplied at a later stage of the esterification stepat which the esterification ratio reaches to the prescribed level or tothe esterification reaction product during the transportation from theesterification step to the melt polycondensation step, preferably to theesterification reaction product during the transportation from theesterification step to the melt polycondensation step. By the additionat this position, not only the amount of by-production of diethyleneglycol units will be suppressed, but also precipitation of solid foreignmatters will be suppressed, the polymerizability will be good. Andthermal decomposition reactions will be suppressed, whereby in theobtainable resin, the carboxylic acid terminal number or the amount ofby-products such as acetaldehyde can be suppressed to a low level.

The reasons why the above-described positions for addition of therespective catalyst components are preferred, are not clearlyunderstood. However, basically, it is considered that acid catalystssuch as the antimony compound, and the titanium compound, the zirconiumcompound, the hafnium compound, the aluminum compound, the zinccompound, the gallium compound or the germanium compound, are addedpreferably immediately before the polycondensation step, as theyincrease the amount of by-production of diethylene glycol units, whilebasic catalysts such as the compound of Group IA element except forhydrogen and/or the compound of Group IIA element, are added preferablyat the initial stage, as they suppress the amount of by-production ofdiethylene glycol units, but if they are added too early in the initialstage, they will cause precipitation of solid foreign matters, thermaldecomposition reactions or other side reactions for e.g. acetaldehyde.Accordingly, it is considered preferred to add them at a stage where theesterification ratio is at least 90%. The phosphorus compound, addedfirst as a buffer agent for the above-described various catalysts, isbelieved to suppress abrupt catalytic actions, whereby the reactions forthe production will be easily controlled as a whole, and also with theobtainable polyester, the heat stability will be improved, and theacetaldehyde content or the like will be reduced.

Use of the Polyester Resin

The polyester resin thus obtained is useful particularly for a hollowcontainer for a non-carbonated beverage, whereby a container havingexcellent transparency, heat resistance and strength can be produced ata productivity higher than ever, while suppressing elution of antimony.Specifically, it is preferably molded into a preform having a bottomedtubular shape by injection molding, and then this preform is subjectedto stretch blow molding to produce a bottle for a beverage. With respectto the temperature conditions for the injection molding, the moldtemperature is from 0 to 30° C., and the resin temperature is from themelting point to 350° C., preferably from the melting point +10° C. to320° C. For the stretch blow molding, the reheating temperature of thepreform is from 70 to 130° C., preferably from 80 to 125° C., and themold temperature is from room temperature to 200° C., preferably fromroom temperature to 180° C. Further, in a case where heat treatment isapplied to the molded product to improve the heat resistance, such heattreatment may be carried out form 70 to 200° C., preferably from 90 to180° C. The most preferred temperature is from 120° C. to 160° C.Further, at the time of the production of a molded product, usualadditives such as a nucleating agent, a lubricant, a stabilizer, anantistatic agent, an antifogging agent, a colorant, etc., may beincorporated, as the case requires.

Preferred Embodiment as a Bottle for a Carbonated Beverage

The polyester resin of the present invention is preferably polyester{circle around (3)} as disclosed in Disclosure of the Invention, for thepurpose of obtaining a bottle excellent in transparency, strength,taste-deterioration resistance of e.g. a contained beverage andenvironmental stress cracking resistance, while suppressing elution ofantimony. Such an embodiment will be described in detail.

Monomer Components Constituting the Resin

The polyester resin of this embodiment is preferably a polycondensate ofthe dicarboxylic acid component wherein terephthalic acid or itsester-forming derivative constitutes at least 96 mol % of the totaldicarboxylic acid component and the diol component wherein ethyleneglycol constitutes at least 97 mol % of the total diol component, andpreferably one wherein ethylene terephthalate units made of themconstitute at least 96 mol % of the constituting repeating units. If theethylene terephthalate units are less than 96 mol %, the mechanicalstrength or heat resistance tends to be poor as a molded product such asa bottle.

Antimony, Phosphorus and Other Constituting Element Components

The polyester resin of this embodiment preferably contains an antimonycompound or/and a titanium compound in such ranges that the content(ppm) as antimony atoms (Sb) and the content (ppm) as titanium atoms(Ti) satisfy the following formulae:

10≦Sb≦200

0≦Ti≦10

150≦100Ti+Sb≦1, 200

If the content as antimony atoms (Sb) exceeds the above range, thetransparency tends to deteriorate as a molded product such as a bottle,and if the content as titanium atoms (Ti) exceeds the above range, thecolor tone tends to deteriorate.

Further, if (100Ti+Sb) is less than the above range, thepolycondensability tends to be inadequate. On the other hand, if itexceeds the above range, increase of the amount of acetaldehyde will besubstantial, and the thermal stability tends to be low, as a moldedproduct such as a bottle.

Further, the polyester resin of this embodiment contains a compound of ametal element of Group IA or IIA of the periodic table and a phosphoruscompound, from the viewpoint of the polycondensability, reduction ofby-products such as acetaldehyde and cyclic trimers, as well as thetransparency, the color tone, etc. of the obtainable resin. Itpreferably contains the above compounds of metal elements in an amountof from 0.2 to 5 mol/ton (from 5 to 121 ppm) as the total (M) of suchatoms and the phosphorus compound in an amount of from 0.1 to 6.5mol/ton (from 3 to 200 ppm) as phosphorus atoms (P). It is morepreferred that it contains the above-mentioned metal element compoundsin an amount of from 0.3 to 3 mol/ton (from 8 to 72 ppm) as the total(M) of their atoms and the phosphorus compound in an amount of from 0.2to 2 mol/ton (from 7 to 61 ppm) as phosphorus atoms (P).

As the phosphorus compound, orthophosphoric acid, tris(triethyleneglycol)phosphate, ethyl diethyl phosphonoacetate, ethyl acid phosphate,triethylene glycol acid phosphate or phosphorous acid may, for example,be preferred. Particularly preferred is tris(triethyleneglycol)phosphate, ethyldiethyl phosphonoacetate, ethyl acid phosphate ortriethylene glycol acid phosphate.

Further, at the time of polycondensation, a metal compound other thanthe above-mentioned various compounds may be coexistent within a rangenot to impair the effects of the present invention. Accordingly, thepolyester resin of the present invention may contain the metal compound.The metal compound in such a case, may, for example, be a compound suchas an oxide, hydroxide, alkoxide, carbonate, phosphate, carboxylate orhalide of aluminum, chromium, iron, cobalt, nickel, copper, zinc,germanium, zirconium, molybdenum, silver, tin, lanthanum, cerium,hafnium, tungsten or gold.

Physical Properties of Polyester {circle around (3)}

The polyester resin of this embodiment satisfies the followingcharacteristics (A), (B) and (C):

(A) after formed into a molded product, the temperature-risingcrystallization temperature (Tc₁) is at least 155° C., and thetemperature-lowering crystallization temperature (Tc₂) is at most 180°C. or not observed,

(B) the difference (ΔAA=AA_(s)−AA_(o)) between the acetaldehyde content(AA_(s); ppm) in a molded product after injection molding at 280° C. andthe acetaldehyde content (AA_(o); ppm) before the injection molding, isnot more than 15 ppm, and

(C) when an injection-molded sheet having a thickness of 1 mm isimmersed in a 0.2 wt % sodium hydroxide aqueous solution at 25° C. insuch a state that it is fixed along the outer circumference of acylinder having a diameter of 32mm, the environmental stress rupturetime is at least 10 minutes.

The polyester resin of this embodiment is preferably such that afterformed into a molded product, the temperature-rising crystallizationtemperature (Tc₁) is at least 155° C., and the temperature-loweringcrystallization temperature (Tc₂) is at most 180° C. or not observed,and the temperature-rising crystallization temperature (Tc₁) is morepreferably at least 157° C., and the temperature-loweringcrystallization temperature (Tc₂) is more preferably at most 178° C. ornot observed. If the temperature-rising crystallization temperature(Tc₁) is less than the above range, or if the temperature-loweringcrystallization temperature (Tc₂) exceeds the above range, thetransparency tends to be poor as a molded product such as a bottle.

Here, for the temperature-rising crystallization temperature (Tc₁) afterformed into a molded product, a preform after injection molding at 280°C. is heated from 20° C. to 285° C. at a rate of 20° C./min in anitrogen stream by a differential scanning calorimeter (“DSC220C”manufactured by Seiko Denshi K. K.) and the temperature-risingcrystallization temperature is one obtained by measuring thecrystallization heat generation peak temperature as observed during thetemperature rise, and for the temperature-lowering crystallizationtemperature (Tc₂), the preform is heated from 20° C. to 285° C. at arate of 20° C./min, maintained in a molten state at 285° C. for 5minutes and then cooled to 20° C. at a rate of 10° C./min, and thetemperature-lowering crystallization temperature is one obtained bymeasuring the crystallization heat generation peak temperature asobserved during the temperature drop.

The polyester resin of this embodiment is preferably such that thedifference (ΔAA=AA_(s)−AA_(o)) between the acetaldehyde content (AA_(s);ppm) in a molded product after injection molding at 280° C. and theacetaldehyde content (AA_(o); ppm) before the injection molding, is notmore than 15 ppm. The difference (AA_(s)−AA_(o)) is more preferably notmore than 13 ppm. If ΔAA exceeds the above range, the tastedeterioration resistance of the contained beverage or the like tends todeteriorate as a molded product such as a bottle.

The polyester resin of this embodiment is preferably such that when aninjection-molded sheet having a thickness of 1 mm is immersed in a 0.2wt % sodium hydroxide aqueous solution at 25° C. in such a state that itis fixed along the outer circumference of a cylinder having a diameterof 32 mm, the environmental stress rupture time is at least 10 minutes.Such environmental stress rupture time is more preferably at least 12minutes.

Here, for the environmental stress rupture time, an injection-moldedsheet having a length of 50 mm, a width of 6 mm and a thickness of 1 mmis immersed in a 0.2 wt % sodium hydroxide aqueous solution at 25° C. insuch a state that it is fixed along the outer circumference of acylinder having a diameter of 32 mm with both ends in the lengthdirection of the molded sheet extending over a half circumference of theouter circumference of the cylinder, whereby the time until the rupturetakes place, is measured as the environmental stress rupture time.

Further, the polyester resin of this embodiment preferably satisfiesalso the following characteristics (D), (E) and (F):

(D) the proportion of diethylene glycol in the diol component in theresin is not more than 2.0 mol %,

(E) the carboxylic acid terminal amount (AV) is from 20 to 50equivalents/ton resin, and

(F) the intrinsic viscosity [ n ] is from 0.75 to 1.0 dl/g.

The polyester resin of this embodiment is such that the proportion ofdiethylene glycol in the diol component in the resin is preferably notmore than 2.0 mol %, more preferably not more than 1.8 mol %,particularly preferably not more than 1.6 mol %. If the proportion ofdiethylene glycol in the diol component exceeds the above range, theenvironmental stress cracking resistance tends to be poor as a moldedproduct such as a bottle. Further, the carboxylic acid terminal amountis measured by the method disclosed in Examples relating to polyester{circle around (3)} in the Examples given hereinafter.

Further, the polyester resin of this embodiment is such that thecarboxylic acid terminal amount is preferably from 20 to 50equivalents/ton resin. If the carboxylic acid terminal amount is lessthan the above range, the environmental stress cracking resistance tendsto be poor as a molded product such as a bottle. On the other hand, ifit exceeds the above range, the thermal stability, etc., tend to bepoor.

Further, the polyester resin of this embodiment is such that theintrinsic viscosity [η] is preferably from 0.75 to 1.0 dl/g, morepreferably from 0.80 to 0.90 dl/g. If the intrinsic viscosity is lessthan the above range, the mechanical strength such as environmentalstress cracking resistance tends to be inadequate as a molded productsuch as a bottle, and in molding such as stretch blow molding, uniformstretching tends to be difficult. On the other hand, if it exceeds theabove range, the moldability tends to be low, and a problem such that inmolding such as stretch blow molding, a molded product tends to break bythe blow pressure.

Further, the polyester resin of this embodiment preferably satisfiesalso the following characteristic (G):

(G) The absorbance at a wavelength of 1,000 nm in the form of aninjection-molded plate having a thickness of 4 mm, is from 0.06 to 0.20.

The polyester resin of this embodiment is such that the absorbance at awavelength of 1,000 nm in the form of an injection-molded plate having athickness of 4 mm, is preferably from 0.04 to 0.20, more preferably from0.06 to 0.15. If the absorbance is less than the above range, it takestime for heat treatment during molding of a bottle, whereby theproductivity tends to be low, or the shape of the mouth stopper portion,etc. tends to deteriorate due to heat treatment. On the other hand, ifit exceeds the above range, the transparency tends to be poor as amolded product such as a bottle.

Production Process

As described above, the polyester resin whereby, particularly whenformed into a bottle for a carbonated beverage, it is possible to obtaina bottle excellent in transparency, strength, taste-deteriorationresistance of contained beverage, etc., and environmental stresscracking resistance, while suppressing elution of antimony, can beobtained by the above-mentioned process for producing a polyester tosuppress elution of antimony, preferably by adjusting the amount of thecopolymerizable component, the amount of contained atoms, the carboxylicacid terminal number, the intrinsic viscosity, etc., to be within theabove-mentioned ranges in accordance with conventional methods bycontrolling the feed materials, the charged catalyst composition, theoperation conditions, etc. at the time of the production.

Application Example of Polyester {circle around (3)}

The polyester resin of this embodiment thus obtained is usefulparticularly for a bottle for a carbonated beverage, whereby it ispossible to obtain a bottle excellent in transparency, strength,taste-deterioration resistance of the contained beverage, whilesuppressing elution of antimony.

Specifically, it will be melt plasticized by a usual method to obtain amolding material. And, it is suitably used for molding an injection blowbottle to mold a bottle by stretch blow molding by biaxially stretchingin a blow molding mold, after forming a preform by injection molding.The injection molding conditions at that time may be within ranges whichare commonly employed. For example, the cylinder temperature is from260° C. 300° C., the screw rotational speed is from 40 to 300 rpm, theinjection pressure is from 4×10⁶ to 14×10⁶ Pa, and the mold temperatureis from about 5 to 40° C., and with respect to the stretch blow moldingconditions, the stretch temperature is from 70 to 120° C., thestretching ratio is from 1.5 to 3.5 times in the longitudinal directionand from 2 to 5 times in the circumferential direction. Further, heatset is carried out for a few second to a few minutes at a temperature offrom 100 to 200° C.

The polyester resin of this embodiment is suitable for molding of aninjection blow bottle wherein a preform obtained by injection molding isreheated and then molded into a bottle by blow molding, and it isparticularly suitable for a bottle for a carbonated beverage. Preferredembodiment for hot filling The polyester resin of the present inventionis preferably the above-mentioned polyester {circle around (4)} for thepurpose of obtaining a bottle which is free from deterioration of thetransparency of the body portion, which is excellent in the productivityof a hollow container as the crystallization rate of the mouth stopperportion is high and which is excellent in the dimensional stability ofthe mouth stopper portion and which has little deformation at the mouthstopper portion, while suppressing elution of antimony, in a case whereit is formed into a hollow container to be used particularly by heatsterilization filling for both non-carbonated and carbonated beverages.Such an embodiment will be described in detail.

Monomer Components Constituting the Resin

The polyester resin of this embodiment is one containing an ethyleneterephthalate unit as the main constituting repeating unit and ispreferably a polycondensate of a dicarboxylic acid component whereinterephthalic acid or its ester-forming derivative such as an alkyl esterhaving from about 1 to 4 carbon atoms, constitutes at least 98 mol % ofthe total dicarboxylic acid component, with a diol component whereinethylene glycol constitutes at least 95 mol % of the total diolcomponent. It is more preferably the one wherein this ethyleneterephthalate unit constitutes at least 93 mol % of the constitutingrepeating units. If the ethylene terephthalate unit is less than 93 mol%, the mechanical strength or the heat resistance tends to be poor as amolded product.

Antimony and Phosphorus

In the polyester resin of this embodiment, the content of the antimonycompound is from 0.08 to 2 mol (from 10 to 243 ppm), preferably from 0.2to 1.7 mol (from 25 to 206 ppm), as antimony atoms (Sb), per 1 ton ofthe polyester resin. If the content as antimony atoms (Sb) in theantimony compound is less than the above range, the polycondensabilitytends to deteriorate, and the content of cyclic trimers, etc. asby-products, tends to be large. On the other hand, if it exceeds theabove range, elution of the antimony compound tends to increase, whenused as a bottle or the like.

The content of the phosphorus compound in the polyester resin ispreferably from 0.1 to 7 mol (from 4 to 216 ppm), more preferably from0.3 to 4 mol (from 10 to 123 ppm) as phosphorus atoms (P), per 1 ton ofthe polyester resin.

As the phosphorus compound, the same one as described in the preferredembodiment for a bottle for a carbonated beverage, is preferred.

Other Components

Further, the polycondensation of the polyester resin of this embodimentis preferably one carried out in the coexistence of a titanium compound,and accordingly, the polyester resin contains such a titanium compound.The amount of the titanium compound used for the polycondensation andthe resulting content in the polyester resin, are preferably not morethan 0.2 mol (9 ppm), more preferably from 0.001 to 0.1 mol (from 0.05to 5 ppm), as titanium atoms (Ti) per 1 ton of the polyester resin. Ifthe content of the titanium compound is less than the above range, thedegree of improvement in the transparency as the polyester resin tendsto be low. On the other hand, if it exceeds the above range, the colortone tends to deteriorate.

Further, the polycondensation of the polyester resin is preferably onecarried out in the coexistence of a compound of an element of Group IAor IIA of the periodic table, from the viewpoint of thepolycondensability, and reduction of by-products such as cyclic trimersand acetaldehyde, as well as the transparency, the color tone, etc. ofthe obtainable resin. Accordingly, the polyester resin contains thecompound of such an element. The amount of the compound of such anelement to be used for polycondensation, and the resulting content inthe polyester resin, are preferably from 0.4 to 8 mol (from 9 to 194ppm), more preferably from 0.6 to 4 mol (from 14 to 97 ppm), as thetotal of atoms of the compound of such an element, per 1 ton of thepolyester resin.

Physical Properties and Process for Producing Polyester {circle around(4)}

The polyester resin of this embodiment is such that the intrinsicviscosity [η] is preferably from 0.6 to 1.0 dl/g, more preferably from0.7 to 1.0 dl/g. If the intrinsic viscosity is less than the aboverange, the mechanical strength as the polyester resin tends to beinadequate, and uniform stretching tends to be difficult in molding suchas stretch blow molding. On the other hand, if it exceeds the aboverange, the moldability tends to deteriorate, and there will be a problemthat in molding such as stretch blow molding, the molded product islikely to break by the blow pressure.

And, the polyester resin of this embodiment preferably contains apolyolefin resin or a polyamide resin, and the polyolefin resin or thepolyamide resin is preferably contained in an amount of from 0.0001 to1,000 ppm, more preferably from 0.001 to 100 ppm. Here, if the contentof the latter polyolefin resin or the polyamide resin is less than theabove range, the crystallization rate at the mouth stopper portion tendsto be low when formed into a hollow container, and consequently, theproductivity of the bottle deteriorates. On the other hand, if itexceeds the above range, the transparency tends to be poor.

Here, the polyolefin resin may, for example, be a homopolymer of ana-olefin having from about 2 to 8 carbon atoms, such as ethylene,propylene or butene-1, or a copolymer of such an a-olefin with anothera-olefin having from about 2 to 20 carbon atoms, such as ethylene,propylene, 1-butene, 3-methyl-1-butene, 1-pentene, 4-methyl-l-pentene,1-hexene, 1-octene or 1-decene or with a vinyl compound such as vinylacetate, acrylic acid, methacrylic acid, an acrylate, a methacrylate,vinyl chloride or styrene. Specifically, for example, an ethylenehomopolymer such as a low, intermediate or high density polyethylene(branched or linear), an ethylene type resin such as anethylene/propylene copolymer, an ethylene/1-butene copolymer, anethylene/4-methyl-1-pentene copolymer, an ethylene/1-hexene copolymer,an ethylene/1-octene copolymer, an ethylene/vinyl acetate copolymer, anethylene/acrylic acid copolymer, an ethylene/methacrylic acid copolymeror an ethylene/ethyl-acrylate copolymer, a propylene homopolymer, apropylene type resin such as a propylene/ethylene copolymer orpropylene/ethylene/1-butene copolymer, and a 1-butene homopolymer, a1-butene type resin such as a 1-butene/ethylene copolymer or a1-butene/propylene copolymer, may be mentioned.

Further, the polyamide resin may, for example, be a polymer of a lactamsuch as butyrolactam, δ-valerolactam, E-caprolactam, enantholactam orω-lauryllactam, a polymer of an amino acid such as 6-amino caproic acid,7-amino heptanoic acid, 8-amino octanoic acid, 9-amino nonanoic acid,11-amino undecanoic acid or 12-amino dodecanoic acid, a polycondensateof a diamine, such as an aliphatic diamine such as 1,4-butane diamine,1,5-pentane diamine, 1,5-hexane diamine, 1,6-hexane diamine, 1,9-nonanediamine, 1,11-undeca diamine, 1,12-dodecane diamine or α,ω-diaminopolypropylene glycol, an alicyclic diamine such as 1,3- or1,4-bis(aminomethyl)cyclohexane or bis(p-aminocyclohexylmethane), or anaromatic diamine such as m- or p-xylylene diamine, with a dicarboxylicacid, such as an aliphatic dicarboxylic acid such as glutaric acid,adipic acid, suberic acid, sebacic acid or dodecanoic diacid, analicyclic dicarboxylic acid such as cyclohexane dicarboxylic acid, or anaromatic dicarboxylic acid such as terephthalic acid or isophthalicacid, or a copolymer thereof. Specifically, for example, nylon 4, nylon6, nylon 7, nylon 8, nylon 9, nylon 11, nylon 12, nylon 66, nylon 69,nylon 610, nylon 611, nylon 612, nylon 6T, nylon 61, nylon MXD6, nylon6/66, nylon 6/610, nylon 6/12, nylon 6/6T or nylon 6I/6T may bementioned.

Further, in this embodiment, the above polyolefin resin or the polyamideresin may be incorporated to the polyester resin by a common method suchas a method of directly adding and melt mixing or a method of adding andmelt mixing as a master batch the above polyolefin resin or thepolyamide resin to the above polyester resin so that its content becomeswithin the above-mentioned range. Otherwise, a method may be employedwherein the above polyolefin resin or the polyamide resin is directlyadded as a powder at a production stage of the above polyester resin,for example, at any stage of e.g. during the melt polycondensation (thestarting materials, slurry, catalyst, etc.), immediately after the meltpolycondensation, immediately after the preliminary crystallization,during the solid phase polycondensation or immediately after the solidphase polycondensation, or a liquid such as water having the powderdispersed therein is contacted with the polyester resin chips, a gassuch as air having the powder included is contacted with the polyesterresin chips, or the polyester resin chips are contacted to a componentmade of the polyolefin resin or the polyamide resin under a flowingcondition, followed by melt kneading.

Among these methods, as a method of adding the polyolefin resin or thepolyamide resin in the form of a powder, a method is preferred in whicha powder of the polyolefin resin or the polyamide resin is incorporatedto air for pneumatic transportation at the time of pneumatictransportation to a preliminary crystallization machine or at the timeof pneumatic transportation to a solid polycondensation tank, of chipsof the polyester resin after the melt polycondensation, or at the timeof pneumatic transportation to a storage tank or at the time ofpneumatic transportation to a molding machine, of chips after the solidphase polycondensation.

Further, as a method of contacting the polyester resin chips to acomponent made of the polyolefin resin or the polyamide resin under aflowing condition, it is preferred that in a space wherein the componentmade of the polyolefin resin or the polyamide resin is present, thepolyester resin chips are brought in collision and contacted with thecomponent. Specifically, a method may, for example, be mentioned inwhich a part of a pneumatic transportation pipe, a gravitytransportation pipe, a silo, a punching plate or a vibration sieve, amagnet portion of a magnet catcher, etc. in the production step such asimmediately after the melt polycondensation of the polyester resin,immediately after the preliminary crystallization or immediately afterthe solid polycondensation, or at the time of charging or dischargingthe transport container in e.g. the transportation stage as a product ofpolyester resin chips, or at the time of introducing into the moldingmachine at the molding stage of the polyester resin chips, is made ofthe polyolefin resin or the polyamide resin, or the polyolefin resin orthe polyamide resin is lined, or in the above-mentioned transportchannel, the component made of the polyolefin resin or the polyamideresin is installed in the form of a rod or net, whereby the polyesterresin chips are transported. The contact time of the polyester resinchips with the above component is usually a very short time at a levelof from 0.01 to 1 second, whereby a very small amount of the polyolefinresin or the polyamide resin can be included in the polyester resin.

And, the polyester resin of this embodiment is such that thetemperature-rising crystallization temperature (Tc₁) after formed into amolded product is preferably from 155 to 165° C., and thetemperature-lowering crystallization temperature (Tc₂) is preferably atmost 180° C. or not observed. The temperature-rising crystallizationtemperature (Tc₁) is more preferably from 157 to 164° C., and thetemperature-lowering crystallization temperature (Tc₂) is morepreferably at most 178° C. or not observed. Here, if thetemperature-rising crystallization temperature (Tc₁) is less than theabove range, the transparency tends to be poor as the polyester resincomposition. On the other hand, if it exceeds the above range, it takestime for heat treatment at the time of molding a bottle, whereby theproductivity tends to be low, or the shape of e.g. the mouth stopperportion tends to deteriorate due to the heat treatment. Further, if thetemperature-lowering crystallization temperature (Tc2) exceeds the aboverange, the transparency tends to be poor as a polyester resin.

Here, for the temperature-rising crystallization temperature (Tc₁) afterformed into a molded product, a preform after injection molding at 280°C., was heated from 20° C. to 285° C. at a rate of 20° C./min in anitrogen stream by a differential scanning calorimeter (“DSC220C”,manufactured by Seiko Denshi K. K.), and the crystallization heatgeneration peak temperature observed in the temperature rise, wasmeasured as the temperature-rising crystallization temperature, and forthe temperature-lowering crystallization temperature (Tc₂), the preformwas heated from 20° C. to 285° C. at a rate of 20° C./min, maintained ina molten state at 285° C. for 5 minutes and then cooled to 20° C. at arate of 10° C./min, and the crystallization heat generation peaktemperature observed during the temperature drop was measured as thetemperature-lowering crystallization temperature.

Further, the polyester resin of this embodiment is such that the cyclictrimer content (CT_(o)) is preferably not more than 0.45 wt % from theviewpoint of the mold contamination resistance during the molding.Further, from the viewpoint of e.g. the taste-deterioration resistanceof the contained beverage when used as a bottle or the like, theacetaldehyde content (AA_(o)) is preferably not more than 10 ppm, andfrom the viewpoint of e.g. the color tone as a bottle or the like, thecolor coordinate b of the Hunter's color difference formula in the Labcolor system disclosed in Reference 1 of JIS Z8730 is preferably notmore than 4. The cyclic trimer content (CT_(o)) is more preferably notmore than 0.40 wt %, the acetaldehyde content (AA_(o)) is morepreferably not more than 5 ppm, and the color coordinate b of Hunter'scolor difference formula is more preferably not more than 3.

Further, from the viewpoint of e.g. the mold contamination resistanceduring the molding, the polyester resin of this embodiment is such thatthe difference (CT_(s)−CT_(o)) between the cyclic trimer content(CT_(s); wt %) in a molded product after injection molding at 280° C.and the cyclic trimer content (CT_(o); wt %) before the injectionmolding, is preferably not more than 0.15 wt %, more preferably not morethan 0.10 wt %. Further, from the viewpoint of e.g. thetaste-deterioration resistance of the contained beverage when used as abottle or the like, the difference (AA_(s)−AA_(o)) between theacetaldehyde content (AA_(s); ppm) in a molded product after injectionmolding at 280° C. and the acetaldehyde content (AA_(o); ppm) before theinjection molding, is preferably not more than 20 ppm, more preferablynot more than 15 ppm.

Use of Polyester Resin {circle around (4)}

The polyester resin thus obtained is useful as a hollow container to beused for hot filling for both non-carbonated and carbonated beverages,whereby it is possible to obtain a bottle which is free fromdeterioration of the transparency of the body portion, which isexcellent in the productivity of a hollow container as thecrystallization rate at the mouth stopper portion is high, and which isexcellent in the dimensional stability of the mouth stopper portion andhas little deformation of the mouth stopper portion during hot filling,while suppressing elution of antimony.

Specifically, it is useful, for example, for molding of an injectionblow molded product, wherein a preform is formed by injection moldingand then biaxially stretched in a blow molding mold for stretch blowmolding to form a bottle or the like, and it is particularly suitablefor molding a hollow container to be used by heat sterilization filling,by heat treating the preform or the mouth stopper portion of a bottle bye.g. an infrared ray heater. The injection molding conditions at thattime are within the ranges which are commonly employed. For example, thecylinder temperature is from 260° C. to 300° C., the screw rotationalspeed is from 40 to 300 rpm, the injection pressure is from 4×10⁶ to14×10⁶ Pa, and the molding temperature is from about 5 to 40° C.Further, as the stretch blow molding conditions, the stretchingtemperature is from 70 to 120° C., the stretching ratio is from 1.5 to3.5 times in a longitudinal direction and from about 2 to 5 times in thecircumferential direction, and further, heat fixing is carried out for afew second to a few minutes at a temperature of from 100 to 200° C.

Further, among the molded products by the above-mentioned moldingmethods, it is suitable particularly for an injection blow bottle whichis molded into a bottle by a blow molding method such as a cold parisonmethod wherein a preform obtained by an injection molding method isreheated and then biaxially stretched, and for example, it is suitablefor a hollow container used by heat sterilization filling of a beverageor the like such as a fruit juice beverage, tea or mineral water.

Further, an injection blow bottle having a specific surface area of from0.6 to 0.8 cm⁻¹ obtainable from the polyester resin of this embodimentwill have an excellent antimony compound elution resistance whereby theamount of elution of an antimony compound when filled with hot water of93° C. is not more than 1.0 ppb as the concentration of antimony atoms(Sb) in water. Here, the specific surface area of the bottle is a valueobtained by dividing the inner surface area of the bottle by the volumeof the bottle.

Preferred Embodiment as for Fibers and Films

The polyester resin of the present invention is preferably theabove-mentioned polyester {circle around (6)} for the purpose of formingfibers or films by minimizing the number of particles in the interior ofthe resin while suppressing elution of the antimony, so that there willbe no substantial thread breakage or film rupture caused by theparticles, and when formed into a molded product such as a film, therewill be no substantial projections such as fish eyes formed on thesurface. Such an embodiment will be described in detail.

Constituting Monomer Components

A preferred amount of terephthalic acid or its ester-forming derivative,is at least 95 mol %, more preferably at least 98.5 mol %, furtherpreferably 100 mol %, of the dicarboxylic acid component, and thepreferred amount of ethylene glycol is at least 95 mol %, preferably atleast 97 mol %, further preferably at least 98 mol %, of the diolcomponent.

As the diol component, diethylene glycol (usually considered to beformed as a by-product from ethylene glycol) formed as a by-product inthe reaction system, may be copolymerized, and the content of thediethylene glycol component inclusive of one added as a copolymerizablecomponent from outside of the system, is preferably not more than 3 mol%, more preferably from 0.5 mol % to 2.5 mol %, further preferably from1.0 mol % to 2.0 mol %.

If the amount of the copolymerizable component is larger than the aboverange, it tends to be difficult to obtain sufficient heat resistance andstrength when formed into a molded product, and if the amount of thecopolymerizable component is smaller than the above range, thetransparency tends to be poor when formed into a molded product.

Physical Properties of the Resin

The polyester resin of this embodiment is such that the number ofparticles of at least 1 μm in the interior of the resin is not more than20 particles/0.01 mm³. Such a number of particles in the interior of theresin is one obtained by counting the number of particles having a sizeof at least 1 μm in a polyester film obtained by melt-molding apolyester resin, also in the film thickness direction by an imagetreating apparatus by enlarging by means of an interference microscopeand converted to the number of particles per 0.01 mm³, and the detailsare described in Examples.

The number of particles of at least 1 μm in the interior of the resin ispreferably not more than 10 particles/0.01 mm³, more preferably not morethan 5 particles/0.01 mm³, further preferably not more than 3particles/0.01 mm³, particularly preferably not more than 2particles/0.01 mm³, most preferably not more than 1 particle/0.01 mm³.If the number of particles is more than the above range, film rupture orthread breakage is likely to take place due to the stress concentrationon the foreign matters, when films or fibers are molded at a high speed,or when formed into a film or a bottle, projections so-called fish eyesare likely to form on the surface, whereby the appearance tends to beimpaired.

Antimony and Phosphorus

The phosphorus compound to be used, is preferably a pentavalentphosphoric acid ester such as ethyl acid phosphate, from the viewpointof suppressing the number of particles in the resin and from theviewpoint of improving the polymerization rate.

Further, the content of phosphorus atoms based on the obtainablepolyester resin is preferably from 0.1 to 20 ppm, more preferably from 2to 15 ppm, further preferably from 4 to 10 ppm, from the viewpoint ofsuppressing the number of particles in the resin, the polymerizationrate, the heat stability and the volume resistivity of the resin.Namely, if P is less, foreign matters will be less, the volumeresistivity of the resin increases, and the polymerization rate is high,but the color tone tends to deteriorate, and the acid terminal number ofthe resin increases, whereby the melt heat stability tends todeteriorate. If P is large, the tendency tends to be opposite, and inthe above-mentioned range, the foregoing various characteristics aremost well balanced.

The preferred content of phosphorus atoms as mentioned above, isrelatively small as compared with the prior art. According to the priorart, if the content of phosphorus atoms is reduced, the color tone orthe melt heat stability deteriorates to a large extent. Whereas,according to the present invention, by adjusting the contents of variouscompounds derived from the catalysts and the order of additionpreferably to specific ranges, as described hereinafter, variouscharacteristics such as the color tone, the melt heat stability, thevolume resistivity and the polymerizability, can be maintained at goodlevels, while maintaining the number of particles in the resin at alevel substantially small as compared with the prior art.

Further, the total content S of at least one type of atoms selected fromthe group consisting of antimony atoms, aluminum atoms, zinc atoms andgallium atoms, satisfies 10≦S≦200 (weight ppm based on the polyesterresin). The content (Sb) of antimony atoms is preferably Sb≦200, morepreferably 30≦Sb≦150, further preferably 60≦Sb≦100 (each weight ppmbased on the polyester resin).

If the content of antimony atoms is small, the number of particles inthe resin decreases, but the polymerization rate, the color tone, theacid terminal number and the melt heat stability tend to deteriorate. Ifthe content of antimony atoms is large, the number of particles in theresin increases, but the polymerization rate, the color tone, the acidterminal number and the melt heat stability tend to be better. In theabove range, the above-mentioned various characteristics are most wellbalanced.

The content P of phosphorus atoms (weight ppm based on the polyesterresin) and the content Sb of antimony atoms (weight ppm based on thepolyester resin) preferably satisfy 6.0≦Sb/P≦30, more preferably9≦Sb/P≦22.5. The larger Sb/P, the smaller the foreign matters, but if itis small, the polymerization rate tends to be inadequate, and the colortone, the acid terminal number and the melt heat stability tend todeteriorate. Within the above-mentioned ranges of the content P ofphosphorus atoms and the content Sb of antimony atoms, when Sb/P iswithin the above range, the foregoing various physical properties andcharacteristics are most well balanced.

Other Constituting Components

The polyester resin of this embodiment is such that the content T ofeach or a total of the plurality of titanium atoms, zirconium atoms andhafnium atoms, is 0.1≦T≦10 (weight ppm based on the polyester resin).

The titanium atoms, the zirconium atoms and the hafnium atoms arederived from a titanium compound, a zirconium compound and a hafniumcompound to be added as a catalyst at the time of the production of thepolyester resin. If T is large, the polymerization rate will beimproved, but the color tone tends to deteriorate. If T is small, thecolor tone will be good, but the polymerization rate tends todeteriorate. In the above range, various physical properties andcharacteristics will be balanced.

When titanium atoms are contained, the content Ti is preferably 0.5≦Ti≦6(weight ppm based on the polyester resin), more preferably 1≦Ti≦3(weight ppm based on the polyester resin).

The polyester resin of this embodiment is such that the content M ofeach or the total of the plurality of Group IA metal atoms, Group IIAmetal atoms, manganese atoms, iron atoms and cobalt atoms, preferablysatisfies 0.1≦M≦100 (weight ppm based on the polyester resin).

These atoms are derived from compounds to be added as catalysts at thetime of the production of the polyester resin. If M is large, thepolymerization rate will be improved, the color tone will be good, andthe volume resistivity will also increase (will be good), but the acidterminal number and the melt heat stability tend to deteriorate. If M issmall, the acid terminal number and the melt heat stability will begood, but the polymerization rate, the color tone and the volumeresistivity tend to deteriorate. In the above range, various physicalproperties and various characteristics will be balanced.

The polyester resin of this embodiment is such that when it containsmagnesium atoms, their content Mg is preferably 10≦Mg≦70 (weight ppmbased on the polyester resin), more preferably 20≦Mg≦40 (weight ppmbased on the polyester resin).

Further, in such a case, the magnesium content Mg and the content P ofphosphorus atoms preferably satisfy 1.5≦Mg/P≦15 (weight ppm based on thepolyester resin). If Mg/P is large, the polymerization rate will beimproved, the color tone will be good, and the volume resistivity willincrease (will be good), but the acid terminal number, and the melt heatstability tend to deteriorate. If Mg/P is small, the acid terminalnumber and the melt heat stability will be good, but the polymerizationrate, the color tone and the volume resistivity tend to deteriorate.Within the above-mentioned ranges of the phosphorus atom content P andthe magnesium atom content Mg, when Mg/P is within the above range, theforegoing various physical properties and various characteristics willbe most balanced.

Production Process

As the foregoing process for producing a polyester resin which issubstantially free from thread breakage or film rupture caused byparticles at the time of molding fibers or films and which issubstantially free from projections such as fish eyes which are likelyto form on the surface when formed into a molded product such as a filmor a bottle, while suppressing elution of antimony, particularly whileminimizing the number of particles in the interior of the resin, thefollowing embodiment is particularly preferred in addition to the abovedescription of the process for producing a polyester to suppress elutionof antimony.

As between an esterification method and an ester exchange method, theesterification method is preferred. The reason is that if the esterexchange method is adopted, an ester exchange catalyst such as atitanium compound, a magnesium compound, a calcium compound or amanganese compound, is usually required in a relatively large amount,and the number of particles in the resin tends to increase, attributableto such a compound.

The esterification reaction may be carried out solely by theterephthalic acid component and the ethylene glycol component, but itcan also be carried out in the presence of various additives. Forexample, the above-mentioned phosphorus compound, and the antimonycompound, the titanium compound, the zirconium compound, the hafniumcompound, the Group IA metal compound, the Group IIA metal compound, themanganese compound, the iron compound, the cobalt compound, etc. may beadded to the esterification reaction step. Further, if a small amount ofa tertiary amine such as triethylamine, tri-n-butylamine orbenzyldimethylamine, a quaternary ammonium hydroxide such astetraethylammonium hydroxide, tetra n-butylammonium hydroxide ortrimethylbenzylammonium hydroxide, or a basic compound such as lithiumcarbonate, sodium carbonate, potassium carbonate or sodium acetate, isadded, by-production of diethylene glycol from ethylene glycol will besuppressed, whereby the ratio of the diethylene glycol componentcontained in the polyester chain can be made small.

The polyester resin of this embodiment is preferably produced by addingthe above-mentioned various compounds in the amounts within theabove-mentioned ranges in the specific order of addition in theabove-mentioned esterification reaction or ester exchange reaction, andthe subsequent melt polycondensation step.

The phosphorus compound is added preferably at a stage where theesterification ratio is less than 90%. For example, in a case where amultistage reaction apparatus is employed, it is added to the slurrypreparation tank or the first stage of esterification. Preferably it isadded to the slurry preparation tank.

The Group IA metal compound, the Group IIA metal compound, the manganesecompound, the iron compound or the cobalt compound is added preferablyat a stage where the esterification ratio is at least 90%. For examplein a case where a multistage reaction apparatus is employed, it ispreferably added at the second stage of esterification.

The aluminum compound, the zinc compound, the gallium compound, thegermanium compound or the antimony compound is added preferably to thereaction product having an esterification ratio of at least 90%.Specifically, it is supplied at a later stage of the esterification stepat which the esterification ratio reaches that level or to theesterification reaction product during the transportation from theesterification step to the melt polycondensation reaction step.Preferably it is supplied to the esterification reaction product duringthe transportation from the esterification step to the meltpolycondensation reaction step.

The titanium compound, the zirconium compound or the hafnium compound issupplied preferably to the esterification step or to the esterificationreaction product to be supplied to the melt polycondensation reactionstep, and more preferably, it is added to the reaction product at thelater stage of the esterification reaction at which the esterificationratio is at least 90%, and it is added preferably at a step later thanthe addition of the Group IA metal compound or the Group IIA metalcompound. Specifically, it is supplied to a later stage of theesterification step at which the esterification ratio reaches theprescribed level or to the esterification reaction product during thetransportation from the esterification step to the melt polycondensationreaction step. Preferably it is supplied to the esterification reactionproduct during the transportation from the esterification step to themelt polycondensation reaction step.

The reason why the above-described position for addition is preferred,is not necessarily clearly understood. However, by this order ofaddition, not only the number of particles in the resin will besuppressed, but also the carboxylic acid terminal number may besuppressed at a low level, and the polymerization rate may be improved.

Further, from the viewpoint of the production cost, etc., it ispreferred to complete the production by the melt polycondensation, andthe polyester resin obtained by the melt polycondensation issubstantially amorphous, whereby melting when heated is quick, and theproductivity by molding is excellent. The polyester resin of thisembodiment is also preferably the one obtained by the process up to themelt polycondensation.

The intrinsic viscosity (IV) of the polyester resin of this embodimentobtained as described above, is preferably from 0.55 to 0.70 dl/g, morepreferably from 0.58 to 0.68 dl/g. If the intrinsic viscosity is low,the strength or the transparency tends to be poor when formed into amolded product such as a film. If the intrinsic viscosity is high, notonly the productivity of the resin but also the productivity during themolding and the amount of by-products such as acetaldehyde in the moldedproduct tend to deteriorate.

Further, the polyester resin of the present invention is such that thecarboxylic acid terminal number (AV) is preferably not more than 50equivalents/ton. If the carboxylic acid terminal number is large, themelt heat stability tends to be poor, and thermal decomposition orcoloring of the resin during the molding tends to be remarkable.

Further, the polyester resin of this embedment is characterized in thatthe volume resistivity is preferably from 1×10⁰⁶ to 1×10¹⁰ Ω·cm, morepreferably from 1×10⁰⁶ to 1×10⁰⁹ Ω·cm, further preferably from 1×10⁰⁷ to5×10⁰⁸ Ω·cm. The value of the volume resistivity can be adjusted by theamount of the phosphorus compound, the amount of the aluminum compound,the zinc compound, the gallium compound, the germanium compound or theantimony compound, the amount of the Group IA metal compound, the GroupIIA metal compound, the manganese compound, the iron compound or thecobalt compound, or the amount of the titanium compound, the zirconiumcompound or the hafnium compound. When the volume resistivity value iswithin the above range, when formed into a film, the adhesion to thefilm roll is reduced, whereby high speed forming will be possible.Further, the polyester resin of this embodiment is such that value b inthe Hunter's color coordinate system is preferably at most 5, morepreferably at most 3. If value b is high, the color tends to beyellowish when formed into a molded product, thus leading to a problemon appearance.

Further, the polyester resin of this embodiment is such that the contentof the diethylene glycol component is preferably not more than 3 mol %,more preferably from 0.5 mol % to 2.5 mol %, further preferably from 1.0mol % to 2.0 mol %, based on the total diol component. If the amount ofthe diethylene glycol component is large, no adequate heat resistance orstrength tends to be obtained when formed into a molded product, and ifit is small, the transparency tends to deteriorate when formed into amolded product.

Use of Polyester {circle around (6)}

The polyester resin thus obtainable can be made to have a very smallnumber of particles in the interior of the resin while suppressingelution of antimony, so that when formed into fibers or films, threadbreakage or film rupture caused by particles will not substantially takeplace, or when formed into a molded product such as a film, there willbe no substantial projections such as fish eyes on its surface.

For example, it can be formed into various molded products such asfibers, sheets and stretched films, by usual methods. When formed into asheet, this sheet may then be used to form a container by draw forming.

For example, in a case where a film is to be produced, the polyestercomposition is extruded at a temperature of from the melting point (Tm:° C.) to (Tm+70)° C. to obtain a non-stretched film, and thisnon-stretched film is stretched in a monoaxial direction (longitudinaldirection or transverse direction) at a temperature of from (Tg−10) to(Tg+70)° C. (where Tg: glass transition temperature of the polyester) ata stretching ratio of from 2.5 to 5.0 times and then stretched in adirection perpendicular to the above stretching direction (when thefirst stretching is in a longitudinal direction, the second stretchingwill be in a transverse direction) at a temperature of from Tg (° C.) to(Tg+70)° C. at a stretching ratio of from 2.5 to 5.0 times to obtain thefilm. In such a case, the area stretching ratio is preferably from 9 to22 times, more preferably from 12 to 22 times. The stretching means maybe either simultaneous biaxial stretching or successive biaxialstretching.

Further, the obtained film can be heat-set at a temperature of from(Tg+70)° C. to Tm (° C.). For example, in the case of a polyethyleneterephthalate film, heat setting is preferably conducted at atemperature of from 200 to 240° C. The heat setting time is, forexample, from 1 to 60 seconds.

Particularly, the polyester resin of the present invention ischaracterized in that when formed into a biaxially stretched film underthe following conditions, projections on the film surface are preferablysuch that:

those (L1) having heights of at least 0.27 μm and less than 0.54 μm areat most 50/200 cm²,

those (L2) having heights of at least 0.54 μm and less than 0.81 μm areat most 10/200 cm², and

those (L3) having heights of at least 0.81 μm and less than 1.08 μm areat most 3/200 cm².

Projections L1 are more preferably at most 30, further preferably atmost 20, particularly preferably at most 10. Projections L2 are morepreferably at most 5, and projections L3 are more preferably at most 1.

For example, when fibers are to be produced, conventional spinningconditions may be employed. Spinning is carried out at a spinning rateof from 700 to 8,000 m/min, preferably from 2,000 to 5,000 m/min. If thespinning rate is less than 700 m/min, the productivity tends to be low,and the cost tends to be high, such being not practical. Further,spinning at a rate of 8,000 m/min or higher, is preferred from atheoretical production, but a problem which must be solved from anengineering point of view such as an accompanying flow formed at thetime of spinning, tends to be large, and unless the spinning apparatusis improved, thread breakage will be frequented in spinning, such beingundesirable.

The spun yarn thus withdrawn may be once wound up and then subjected tostretching, or without being wound up, may be subjected to stretchingand used as a stretched yarn. The size of yarn is not limited and may befree ranging from a fine yarn of 1 dpf or less to a very thick yarn of100 dpf or more. Depending upon the particular application, falsetwisting or crimping may be applied, and the cross-section of fiber maybe free i.e. may, for example, be circular, triangular or hollow.Further, composite spinning with other material may be possible.

In any case, no adequate strength can be obtained at a stretching ratioof 1.3 times or less. Further, by a usual stretching step, it isdifficult to carry out stretching at a stretching ratio of 3.5 times ormore constantly.

Further, when it is used as a short fiber, the fiber length is, ascommonly known, preferably from 3 to 200 mm, more preferably from 10 to150 mm. Also as commonly known, the crimping degree is preferably from 5to 35%, more preferably fro 8 to 30%.

EXAMPLES

Now, the present invention will be described in further detail withreference to Examples, but the present invention is not limited to thefollowing Examples.

Common analytical and evaluation methods to be used in the Examples willbe listed below. Further, the results are shown in various Tables byusing abbreviations of the following analytical and evaluation methods.

Esterification Ratio

With respect to a solution having a sample dissolved at a concentrationof 3 wt % in a mixed solvent of deuteratedchloroform/hexafluoroisopropanol (weight ratio: 7/3), 1H-NMR wasmeasured by a nuclear magnetic resonance apparatus (“JNM-EX270 model”,manufactured by Nihon Denshi K. K.), and each peak was identified. Thecarboxylic acid terminal amount (A mol/ton sample) was calculated fromthe integral value of the peak, and by the following formula, theesterification ratio (E%) was calculated as a proportion of theesterified among all carboxyl groups of terephthalic acid units.

Esterification ratio (E)=[1-A/((1,000,000/192.2)×2)]×100

Amount of Antimony Eluted From the Polyester Resin Particles

50 g of polyester resin particles having a number average particleweight of 24 mg were heated and crystallized at 120° C. for 10 hours andthen immersed in 150 g of hot water of 95° C. for 60 minutes, wherebyantimony extracted into water was measured as antimony atomconcentration C (ppb) by means of an inductively coupled plasma massspectrometer (“HP4500”, manufactured by Hewlett-Packard Company). By thefollowing formula, the eluted amount D (μg) as antimony atoms per 1 g ofthe polyester resin, was calculated.

D(μg)=(C/10⁹)×(150/50)×10⁶

Content of Metal Atoms

2.5 g of a resin sample was ashed and completely decomposed by hydrogenperoxide in the presence of sulfuric acid in accordance with a usualmethod and then adjusted by distilled water to a constant volume of 50ml, and with respect to this sample, quantitative analysis was carriedout by plasma emission spectrometry by means of a high frequencyinductively coupled plasma emission spectrometer (“JY46P model”,manufactured by JOBIN YVON COMPANY).

Quantitative Determination of Acid Components

With respect to a solution having a sample dissolved at a concentrationof 3 wt % in a mixed solvent of deuteratedchloroform/hexafluoroisopropanol (weight ratio: 7/3), 1H-NMR wasmeasured by a nuclear magnetic resonance apparatus (“JNM-EX270 model”,manufactured by Nippon Denshi K. K.), and peaks of the respective acidcomponents were identified, whereupon from the integral value of a peak,mol % of the particular acid component based on all acid components, wascalculated.

Copolymerized Amount of Diethylene Glycol

With respect to a solution having a resin sample dissolved at aconcentration of 3 wt % in a mixed solvent of deuteratedchloroform/hexafluoroisopropanol (weight ratio: 7/3), 1H-NMR wasmeasured by a nuclear magnetic resonance apparatus (“JNM-EX270 model”,manufactured by Nippon Denshi K. K.), and the respective peaks wereidentified, whereupon from the integral value of a peak, mol % ofdiethylene glycol based on all diol components, was calculated.

Intrinsic Viscosity

0.25 g of a freeze-pulverized resin sample was dissolved at aconcentration (c) of 1.0 g/dl in a mixed solvent ofphenol/tetrachloroethane (weight ratio: 1/1), at 110° C. for 30 minutesin the case of a melt polycondensed resin, or at 120° C. for 30 minutesin the case of a solid phase polycondensed resin, whereupon by means ofan Ubbellohde capillary viscometer, the relative viscosity (ηrel) withthe stock solution was measured at 30° C. A ratio (ηsp/c) of thespecific viscosity (ηsp) obtained from this relative viscosity (ηrel)−1,to the concentration (c), was obtained. In a similar manner, thecorresponding ratios (ηsp/c) were obtained when the concentration (c)was changed to 0.5 g/dl, 0.2 g/dl and 0.1 g/dl, respectively. From thesevalues, a ratio (ηsp/c) when the concentration (c) was extrapolated tobe 0, was obtained as the intrinsic viscosity [η] (dl/g).

Cyclic Trimer Content (CT_(o)) in the Polyester Resin

4.0 mg of a resin sample was accurately weighted and dissolved in 2 mlof a mixed solvent of chloroform/hexafluoroisopropanol (volume ratio:3/2), and then further diluted by an addition of 20 ml of chloroform.Then, 10 ml of methanol was added thereto for precipitation, followed byfiltration to obtain a filtrate, which was evaporated to dryness andthen dissolved in 25 ml of dimethylformamide. The amount of a cyclictrimer (cyclotriethylene terephthalate) in this solution wasquantitatively analyzed by liquid chromatography (“LC-1OA”, manufacturedby Shimadzu Corporation).

Color Coordinate Value b of the Polyester Resin

A resin sample was filled into a cylindrical powder calorimetric cellhaving an inner diameter of 36 mm and a depth of 15 mm to be flush, andby means of a calorimetric color difference meter (“ND-300A”,manufactured by NIPPON DENSHOKU INDUSTRIES CO., LTD.), color coordinateb of the Hunter's color difference formula in the Lab color system asdisclosed in Reference 1 of JIS Z8730, was obtained as a simple averagevalue of values measured at four positions by rotating the cell every900 by a reflection method. At the time of the measurement, theapparatus was preliminarily left to stand for at least 4 hours after thepower source was switched on, to have it sufficiently stabilized beforethe measurement. The lower the value b, the lower the yellowish degree,and the better as the color tone.

Acetaldehyde Content (AA_(o)) in the Polyester Resin

5. 0 g of a resin sample was accurately weighed and sealed in togetherwith 10 ml of pure water in a micro bomb having an internal capacity of50 ml under sealing with nitrogen, whereupon heat extraction was carriedout at 160° C. for 2 hours. The amount of acetaldehyde in the extractedsolution was quantitatively analyzed by gas chromatography (“GC-14A”,manufactured by Shimadzu Corporation) using isobutyl alcohol as theinternal standard and represented by a ratio (ppm) per weight of the PETpolyester.

Acetaldehyde Content (AA_(s)) of the Molded Plate

Using samples cut out in the form of chips of about 4×4 mm from the 4 mmportion (portion B in FIG. 1) and the rear end portion having athickness of 3.5 mm in the molded plate, the measurement was carried outby the same method as described above.

Cyclic Trimer Content (CT_(s)) in the Molded Plate

Using a sample cut out from the forward end portion (portion A inFIG. 1) having a thickness of 3.5 mm in the molded plate, themeasurement was carried out by the same method as described above.

Amount of Antimony Eluted From the Bottle

About 1.5 l of distilled water of 93° C. was filled in a bottle and leftto cool at room temperature, whereupon the concentration (ppb) ofantimony atoms in water was measured by means of an inductively coupledplasma mass spectrometer (“HP4500”, manufactured by Hewlett-PackardCompany).

Color Tone of the Bottle

The color tone of the mouth stopper portion of a bottle was visuallyinspected and evaluated with the following standards:

⊚: colorless transparent.

∘: slightly yellowish, but practically not problematic.

X: yellowish, and practically problematic.

Acetaldehyde Odor of the Bottle

A bottle was heated in an oven at 50° C. for one hour, whereupon theacetaldehyde odor was examined by a sensory test and evaluated with thefollowing standards:

⊚: acetaldehyde odor very little.

∘: acetaldehyde odor little.

X: acetaldehyde odor assails ones nostrils.

Further, abbreviations in the Tables given hereinafter, have thefollowing meanings.

Explanation of Abbreviations:

EAP: ethyl acid phosphate

H3PO4: orthophosphoric acid

H3PO3: phosphorous acid

TMP: trimethyl phosphate

EG: ethylene glycol

DEG copolymerized amount: The copolymerized amount of diethylene glycolin the glycol component. IPA copolymerized amount: The copolymerizedamount of isophthalic acid in the carboxylic acid component.

Sections for the Qualities of Molded Products

280° C. AAs: acetaldehyde content in the stepped molded plateinjection-molded at a cylinder temperature of 280° C.

280° C. ΔAA: difference between 280° C. AAs and the acetaldehyde content(AAo) in the polyester resin.

280° C. CTs: cyclic trimer content in the stepped molded plateinjection-molded at a cylinder temperature of 280° C.

280° C. ΔCT: difference between the 280° C. CTs and the cyclic trimercontent (CTo) in the polyester resin.

280° C. haze: haze at the 5.0 mm portion of the stepped molded plateinjection-molded at a cylinder temperature of 280° C.

270° C. AAs: acetaldehyde content in the stepped molded plateinjection-molded at a cylinder temperature of 270° C.

270° C. CTs: cyclic trimer content in the stepped molded plateinjection-molded at a cylinder temperature of 270° C.

270° C. haze: haze at the 5.0 mm portion of the stepped molded plateinjection-molded at a cylinder temperature of 270° C.

Section for Production Process

A: In the continuous system for an esterification method, the phosphoruscompound was added to the slurry tank, the antimony compound and themagnesium compound were added to the second esterification tank, and thetitanium compound was added into a transportation pipe from the secondesterification tank to the first polymerization tank.

B: In the continuous system for an esterification method, the phosphoruscompound was added to the slurry tank, the magnesium compound was addedto the second esterification tank, and the antimony compound and thetitanium compound were added into a transportation pipe from the secondesterification tank to the first polymerization tank.

C: In the batch system for an esterification method, prior to theinitiation of the polymerization, the phosphorus compound, the magnesiumcompound, the antimony compound and the titanium compound were added inthis order.

D: The batch system for an ester exchange method.

E: A method other than A, B, C and D.

Examples Relating to Polyester {circle around (1)}

Examples from the viewpoint of suppressing elution of antimony, will beshown below.

Example 1-1

Using a continuous polymerization apparatus comprising a slurrypreparation tank, esterification reactors of two stages connected inseries thereto and melt polycondensation tanks of three stages connectedin series to the second stage esterification reactor, terephthalic acidand ethylene glycol were continuously supplied in a weight ratio of865:485 to the slurry preparation tank, and a 0.3 wt % ethylene glycolsolution of ethyl acid phosphate, was continuously added in such anamount that the content as phosphorus atoms (P) based on the formedpolyester resin would be 9 weight ppm, followed by stirring and mixingto obtain a slurry. This slurry was transferred to the first stageesterification reactor set for an average retention time of 4 hours in anitrogen atmosphere at 260° C. under a relative pressure of 50 kPa (0.5kg/cm²G) and then to the second stage esterification reactor set for anaverage retention time of 1.5 hours in a nitrogen atmosphere at 260° C.under a relative pressure of 5 kPa (0.05 kg/cm²G), to carry out theesterification reaction. At that time, the esterification ratio asmeasured by the above-described method, was 85% in the first stage and95% in the second stage.

Further, at that time, via an upper pipe provided at the second stage, a0.6 wt % ethylene glycol solution of magnesium acetate tetrahydrate wascontinuously added in such an amount that the content as magnesium atoms(Mg) based on the formed polyester resin would be 15 weight ppm and a1.9 wt % ethylene glycol solution of antimony trioxide was continuouslyadded in such an amount that the content as antimony atoms (Sb) based onthe formed polyester resin would be 90 weight ppm.

Continuously, at the time of transporting the esterification reactionproduct obtained as described above to the melt polycondensation tank, a0.2 wt % ethylene glycol solution of tetrabutyl titanate, wascontinuously added to the transportation pipe in such an amount that thecontent as titanium atoms (Ti) based on the formed polyester resin wouldbe 2.0 weight ppm, and the esterification reaction product wascontinuously transferred to the first stage melt polycondensation tankset for an average retention time of 1.2 hours at 270° C. under anabsolute pressure of 2.6 kPa (20 Torr), then to the second stage meltpolycondensation tank set for an average retention time of 1.2 hours at278° C. under an absolute pressure of 0.5 kPa (4 Torr) and then to thethird stage melt polycondensation tank set for an average retention timeof 1.2 hours at 280° C. under an absolute pressure of 0.3 kPa (2 Torr),to carry out the melt polycondensation, whereupon the product iswithdrawn in the form of a strand from an outlet provided at the bottomof the polycondensation tank, cooled with water and then cut by a cutterto obtain a polyester resin in the form of chips having a number averageparticle weight of 24 mg. The intrinsic viscosity of the obtained resinwas 0.60 dl/g.

Then, the polyester resin chips obtained as described above werecontinuously supplied for crystallization to an agitationcrystallization machine held at about 160° C. in a nitrogen atmosphereso that the retention time would be about 60 minutes and thencontinuously supplied to a tower type solid polycondensation apparatusand heated at 205° C. in a nitrogen atmosphere for solid phasepolycondensation.

With respect to the obtained solid phase polycondensate resin chips, theeluted amount of antimony was measured by the above-described method,and the results are shown in Table 1.

Further, with respect to the obtained solid phase polycondensate resinchips, the contents as phosphorus atoms (P), magnesium atoms (Mg),antimony atoms (Sb) and titanium atoms (Ti) of the phosphorus component,the magnesium component, the antimony component and the titaniumcomponent, respectively, were measured by the above-described method,and the results are shown in Table 1.

Further, with respect to the obtained solid phase polycondensate resinchips, the copolymerized amount of diethylene glycol, the intrinsicviscosity, color coordinate value b as the color tone and theacetaldehyde content, were measured by the above-described methods, andthe results are shown in Table 1.

Further, the obtained polyester resin chips were dried at 160° C. for 4hours in a nitrogen stream of 40 l/min in an inert oven (“IPHH-201model”, manufactured by ESPEC COMPANY), then, by an injection moldingmachine (“M-70AII-DM”, manufactured by Meiki Co., Ltd.), a steppedmolded plate having a shape shown in FIG. 1 having a size of 50 mm×100mm and thicknesses of six steps ranging from 6 mm to 3.5 mm in atransverse direction with each step being 0.5 mm, was injection-molded(in FIG. 1, G indicates a gate portion) at a cylinder temperature of280° C. under a back pressure of 5×10⁵ Pa at an injection rate of 40cc/sec under a dwell pressure of 35×10⁵ Pa at a mold temperature of 25°C. with a molding cycle of about 75 seconds. With respect to the moldedplate, the acetaldehyde content was measured by the above-describedmethod, and the results are shown in Table 1.

Further, the obtained polyester resin chips were dried at 130° C. for 10hours in a vacuum dryer. Then, by an injection molding machine(“FE-80S”, manufactured by Nissei Plastic Industrial Co., Ltd.), apreform of a test tube shape having an outer diameter of about 29 mm, aheight of about 165 mm, an average wall thickness of about 3.7 mm and aweight of about 60 g, was injection-molded at a cylinder temperature of280° C. under a back pressure of 5×10⁵ Pa at an injection rate of 45cc/sec under a dwell pressure of 30×10⁵ Pa at a mold temperature of 20°C. with a molding cycle of about 40 seconds. The obtained preform washeated for 70 seconds in a near infrared ray irradiation furnaceequipped with a quartz heater and then left to stand at room temperaturefor 25 seconds. Then, it was introduced into a blow mold set at 160° C.and blow-molded under a blow pressure of 7×10⁵ Pa for one second andfurther under a blow pressure of 30×10⁵ Pa for 40 seconds, whilestretching in the height direction by an stretching rod, heat-set andcooled in air to mold a bottle having an outer diameter of about 95 mm,a height of about 305 mm, an average wall thickness of the body portionof about 0.37 mm, a weight of about 60 g, an internal capacity of about1.5 l and a specific surface area of about 0.7 cm⁻¹.

With respect to the obtained bottle, the amount of antimony eluted withhot water, the color tone and the acetaldehyde odor, were measured andevaluated by the above-described methods, and the results are shown inTable 1.

Examples 1-2 to 1-12

A polyester resin was produced in the same manner as in Example 1-1 byusing the compound as identified in Table 1 as the phosphorus compoundand adding it in such an amount that the content as phosphorus atoms (P)based on the formed polyester resin would be the amount as identified inTable 1, and adding other materials in such amounts that the contents asmagnesium atoms (Mg), antimony atoms (Sb) and titanium atoms (Ti), basedon the formed polyester resin, would be the amounts as identified inTable 1. The obtained polyester resin was measured and evaluated in thesame manner as in Example 1-1, and the results are shown in Table 1.

Comparative Example 1-1

A polyester resin was produced in the same manner as in Example 1-1except that a solution of phosphoric acid was used as the phosphoruscompound and added via an upper pipe of the second stage esterificationreactor, the solution of magnesium acetate was added via an upper pipeof the first stage esterification reactor, the solution of antimonytrioxide and the solution of tetrabutyl titanate were added to thetransportation pipe from the second stage esterification reactor to thefirst stage melt polycondensation tank, and the respective compoundswere added in such amounts that the contents of the respective metalatoms based on the formed polyester resin would be the amounts asidentified in Table 1. The obtained polyester resin was measured andevaluated in the same manner as in Example 1-1, and the results areshown in Table 1.

Comparative Example 1-2

A polyester resin was produced in the same manner as in Example 1-1except that no tetrabutyl titanate was added, the solution of antimonytrioxide and the solution of magnesium acetate tetrahydrate were addedto the transportation pipe from the second stage esterification reactorto the first melt polycondensation tank, and the respective compoundswere added in such amounts that the contents of the respective metalatoms based on the formed polyester resin, would be the amounts asidentified in Table 1. The obtained polyester resin was measured andevaluated in the same manner as in Example 1-1, and the results areshown in Table 1.

Comparative Example 1-3

An ester exchange reaction of 100 parts by weight of dimethylterephthalate and 70 parts by weight of ethylene glycol was initiated inaccordance with a usual method by using, as ester exchange catalysts,calcium acetate monohydrate and magnesium acetate tetrahydrate in suchamounts that the contents of the respective metal atoms would be asidentified in Table 1, and after 20 minutes from the initiation ofdistillation of methanol, antimony trioxide was added in such an amountthat the content of the metal atoms would be as identified in Table 1,and the ester exchange reaction was continued. Then, trimethyl phosphatewas added in such an amount that the content of the metal atoms would beas identified in Table 1, and the ester exchange reaction wassubstantially completed. Continuously, tetrabutyl titanate was furtheradded in such an amount that the content of the metal atoms would be asidentified in Table 1, and then, polycondensation was carried out at ahigh temperature high vacuum condition in accordance with a usual methodto produce a polyester resin. The obtained polyester resin was measuredand evaluated in the same manner as in Example 1-1, and the results areshown in Table 1.

TABLE 1 Examples 1-1 1-2 1-3 1-4 1-5 Amount of Sb eluted 0.15 0.18 0.120.09 0.21 (μg/resin) Sb content (ppm) 90 90 90 90 90 Ti content (ppm)2.0 2.0 2.0 2.0 2.0 Mg content (ppm) 15 20 10 5.0 15 Ca content (ppm) 00 0 0 0 P content (EAP) 9 12 6 3 0 (ppm) (H3PO4) 0 0 0 0 9 (H3PO3) 0 0 00 0 Sb/P (weight ratio) 10 7.5 15 30 10 Mg/P (weight ratio) 1.7 1.7 1.71.7 1.7 Production process A A A A A Copolymerized amount 2.4 2.6 2.11.8 1.9 of DEG (mol %) Physical properties of resin Intrinsic 0.78 0.780.78 0.78 0.79 viscosity (dl/g) Color +0.5 +0.1 +0.9 +1.5 +0.3coordinate b AAo (ppm) 0.7 0.8 0.7 0.8 0.8 Quality of molded product280° C. AAs 17.1 17.0 16.4 14.9 14.2 (ppm) 280° C. ΔAA 16.4 16.2 15.714.1 13.4 (ppm) 270° C. haze (%) 25 — — — — 270° C. AAs 11.2 — — — —(ppm) Bottle Amount of Sb 0.2 — — — — eluted (ppb) Color tone ⊚ — — — —Acetaldehyde ⊚ — — — — odor Examples 1-6 1-7 1-8 1-9 1-10 Amount of Sbeluted 0.09 0.14 0.13 0.09 0.13 (μg/resin) Sb content (ppm) 90 90 90 5070 Ti content (ppm) 2.0 2.0 2.0 6.0 3.0 Mg content (ppm) 15 12 25 15 15Ca content (ppm) 0 0 0 0 0 P content (EAP) 0 9 9 9 9 (ppm) (H3PO4) 0 0 00 0 (H3PO3) 9 0 0 0 0 Sb/P (weight ratio) 10 10 10 5.6 7.8 Mg/P (weightratio) 1.7 1.3 2.8 1.7 1.7 Production process A A A A A Copolymerizedamount 98.1 97.4 97.6 96.8 97.2 of EG (mol %) Copolymerized amount 1.92.6 2.4 3.2 2.8 of DEG (mol %) Copolymerized amount 100 100 100 100 100of TPA (mol %) Physical properties of resin Intrinsic 0.78 0.78 0.780.78 0.78 viscosity (dl/g) Color +0.4 +0.9 +3.1 +3.5 +1.5 coordinate bAAo (ppm) 0.8 1.5 3.2 4.7 0.7 Quality of molded product 280° C. AAs 14.117.5 17.6 19.8 17.4 (ppm) 280° C. ΔAA 13.3 16.0 14.4 15.1 16.7 (ppm)270° C. haze (%) — — — 9.2 — 270° C. AAs — — — 13.5 — (ppm) BottleAmount of Sb 0.1 — — 0.1 — eluted (ppb) Color tone ⊚ — — ◯ —Acetaldehyde ⊚ — — ◯ — odor Comparative Example Example 1-11 1-12 1-11-2 1-3 Amount of Sb eluted 0.18 0.28 1.8 1.5 1.2 (μg/resin) Sb content(ppm) 110 150 81 180 47 Ti content (ppm) 1.0 0.5 3.0 0.0 5.0 Mg content(ppm) 15 15 27 57 47 Ca content (ppm) 0 0 0 0 67 P content (EAP) 9 9 090 40 (ppm) (H3PO4) 0 0 26 0 0 (H3PO3) 0 0 0 0 0 Sb/P (weight ratio) 1217 3.1 2.0 1.2 Mg/P (weight ratio) 1.7 1.7 1.0 0.6 1.2 Productionprocess A A E E D Copolymerized amount 97.8 98.0 97.2 97.1 96.5 of EG(mol %) Copolymerized amount 2.2 2.0 2.8 2.9 3.5 of DEG (mol %)Copolymerized amount 100 100 100 100 100 of TPA (mol %) Physicalproperties of resin Intrinsic 0.78 0.78 0.74 0.78 0.72 viscosity (dl/g)Color +0.5 +0.9 +1.1 +0.1 +5.4 coordinate b AAo (ppm) 0.8 0.8 3.4 3.18.2 Quality of molded product 280° C. AAs 16.2 15.0 24.1 20.8 29.4 (ppm)280° C. ΔAA 15.4 14.2 20.7 17.7 21.2 (ppm) 270° C. haze (%) — — — 65 —270° C. AAs — — — — — (ppm) Bottle Amount of Sb — — 1.8 — 1.2 eluted(ppb) Color tone — — ◯ — X Acetaldehyde — — ◯ — X odor

Examples Relating to Polyester {circle around (2)}

Now, Examples for the polyester resin, whereby when it is formed into ahollow container for a non-carbonated beverage, it is possible to obtainthe container excellent in transparency and heat resistance, with aproductivity higher than ever, while suppressing elution of antimony,will be described.

In the Examples of this embodiment, particularly, the following physicalproperties were measured as follows.

Quantitative Analysis of the Glycol Component

50 ml of a 4N-KOH/methanol solution was added to 5 g of a sample resinpulverized by a Willette type pulverizer (model: 1029-A) manufactured byYoshida Co., Ltd. by means of a perforated plate having 1.5 mm holes,and a reflux condenser was set. Then, it was heated and refluxed forhydrolysis for two hours while stirring on a hot plate (surfacetemperature: 200° C.) equipped with a magnetic stirrer. After cooling,about 20 g of high purity terephthalic acid was added, followed byshaking thoroughly for neutralization to obtain a slurry having a pH ofnot higher than 9, which was filtered by means of a 11G-4 glass filterand then washed twice with 2 ml of methanol. The filtrate and thewashing liquids were put together to obtain a sample liquid for gaschromatography. By a microsyringe, 1 μl of the sample liquid wasinjected to a gas chromatography of Shimadzu Corporation (model:GC-14APF), and from the areas of peaks of the respective glycolcomponents, mol % of each glycol component based on the total glycolcomponent was calculated in accordance with the following formula.

mol % of a certain glycol component=(ACO×CfCO)/(Σ(A×Cf))×100

ACO: area of the glycol component (μV·sec)

CfCO: correction coefficient of the glycol component

A: area of each glycol component (μV·sec)

Cf: correction coefficient of each glycol component

The conditions for using the gas chromatography are as follows.

Column: “DB-WAX”, manufactured by J&W (0.53 mm × 30 m) Set temperatures:Column: 160° C. to 220° C. Vaporizing chamber: 230° C. Detector: 230° C.Gas flow rates: Carrier (nitrogen): 5 ml/min Hydrogen: 0.6 kg/cm² Air:0.6 kg/cm² Detector: FID Sensitivity 102 MΩ

Quantitative Analysis of Carboxylic Acid Terminal Mumber (AV)

Chips were pulverized, then dried at 140° C. for 15 minutes by a hot airdrier and cooled to room temperature in a desiccator to obtain a sample.From this sample, 0.1 g was accurately weighed and put into a test tubeand after an addition of 3 ml of benzyl alcohol, dissolved at 195° C.for 3 minutes while blowing dry nitrogen gas thereto. Then, 5 ml ofchloroform was gradually added, followed by cooling to room temperature.To this solution, a phenol red indicator was added in an amount of oneor two drops, followed by titration with a 0.1N sodium hydroxide benzylalcohol solution with stirring while blowing dry nitrogen gas thereto.The titration was terminated at a time point where the color changedfrom yellow to red. Further, as a blank, the same operation was carriedout without using the polyester resin sample, and the acid number wascalculated by the following formula.

Acid number (mol/ton)=(A-B)×0.1×f/W [where A is the amount (μl) of the0.1N sodium hydroxide benzyl alcohol solution required for thetitration, B is the amount (μl) of the 0.1N sodium hydroxide benzylalcohol solution required for the titration of the blank, W is theamount (g) of the polyester resin sample, and f is the titer of the 0.1Nsodium hydroxide benzyl alcohol solution.]

For the titer (f) of the 0.1N sodium hydroxide benzyl alcohol solution,5 ml of methanol was taken into a test tube and, after adding an ethanolsolution of phenol red as an indicator in an amount of one or two drops,titration was carried out to the point of color change with 0.4 ml ofthe 0.1N sodium hydroxide benzyl alcohol solution. Then, 0.2 ml of a0.1N hydrochloric acid aqueous solution having a known titer was addedas a standard solution, followed by titration again to the point ofcolor change with the 0.1N sodium hydroxide benzyl alcohol solution.(The foregoing operation was carried out while blowing dry nitrogen gasthereto.) The titer (f) was calculated by the following formula.

Titer (f)=titer of the 0.1N hydrochloric acid aqueous solution×amount(μl) of the 0.1N hydrochloric acid aqueous solution/titrated amount (μl)of the 0.1N sodium hydroxide benzyl alcohol solution

Temperature-lowering Crystallization Temperature

The obtained resin was dried at 160° C. for 4 hours in a nitrogen streamof 40 l/min in an inert oven (“IPHH-201 model”, manufactured by ESPECCOMPANY). Then, by an injection molding machine (“M-70AII-DM”,manufactured by Meiki Co., Ltd.), a stepped molded plate having theshape as shown in FIG. 1 and having a size of 50 mm×100 mm andthicknesses of six steps ranging from 6 mm to 3.5 mm in a transversedirection with each step being 0.5 mm, was injection-molded at acylinder temperature of 280° C. under a back pressure of 5×10⁵ Pa at aninjection rate of 40 cc/sec under a dwell pressure of 35×10⁵ Pa at amold temperature of 25° C. and with a molding cycle of about 75 seconds.Further, in FIG. 1, G indicates a gate portion.

The forward end portion (portion A in FIG. 1) having a thickness of 3.5mm in the molded plate was cut out and dried at 40° C. for three days ina vacuum dryer, whereupon a sample was cut out from the non-surfaceportion, and about 10 mg of the sample was accurately weighed and sealedin by using an aluminum oven pan and a pan cover (normal pressure type,“P/N SSC000E030” and “P/N SSC000E032”, manufactured by Seiko Denshi K.K.). By means of a differential scanning calorimeter (“DSC220C”,manufactured by Seiko K. K.), it was heated from 20° C. to 285° C. at arate of 20° C./min in a nitrogen stream, then maintained in a moltenstate at 285° C. for 5 minutes and then cooled to 20° C. at a rate of10° C./min, whereby the crystallization peak temperature observed duringthe temperature drop was measured.

Evaluation of Molding of a Bottle

The obtained polyester resin chips were thoroughly dried. Using aninjection molding machine “FE-80S”, manufactured by Nissei PlasticIndustrial Co., Ltd., a preform of a test tube shape having a height of165 mm, an outer diameter of the tube of 29.0 mm, an average wallthickness of 3.7 mm and a weight of 60 g, was injection-molded at aresin temperature of 280° C. under a back pressure of about 5 kg/cm² atan injection rate of about 45 cc/sec under a dwell pressure of about 30kg/cm² at a mold temperature of 20° C. and with a molding cycle of about40 seconds.

Such preforms were introduced into a near infrared ray irradiationfurnace equipped with a quartz heater, and under a constant output, therespective preforms were heated for 56, 58, 60, 62, 64, 66, 68 and 70seconds, respectively, then left at room temperature for 25 seconds andimmediately thereafter, each preform was put into a mold adjusted to160° C. and subjected to blowing under a blow pressure of about 7 kg/cm²for one second and then under a blow pressure of about 30 kg/cm² for 5seconds, while stretching it in the height direction of the bottle by astretching rod, and then maintained for 5 seconds while exerting theblow pressure. After cooling in air, the molded products were taken outto obtain bottles having an average wall thickness of the body portionof 350 μm and a capacity of about 1.5 l.

With respect to these bottles, the transparency at the body portion wasvisually observed, whereby one having good transparency was identifiedby “∘”, one which is slightly foggy but not practically problematic, wasidentified by “Δ”, and one which is foggy and practically notacceptable, was identified by “X”.

Further, the heat resistance of these bottles was evaluated as follows.Namely, a bottle was stored in an environment of 23° C. under a relativehumidity of 50% for one week. Then, to this bottle, hot water of 90° C.was filled at room temperature, and then the bottle was tightly closed.It was laid horizontally for one minute and then held vertically for 5minutes. Thereafter, it was cooled for 20 minutes in water of 10° C. Theshape of the bottle was visually observed, whereby one having no changein shape and good heat resistance, was identified by “⊚”, one having aslight deformation at the body portion but being substantially notproblematic, was identified by “∘”, one having a deformation at the bodyportion and inadequate heat resistance, was identified by “Δ”, and onehaving a large deformation at the body portion and very poor heatresistance, was identified by “X”. By the foregoing evaluation, theminimum heating time of the preform to obtain bottles whereby both thetransparency and the heat resistance are evaluated to be “∘” or “⊚” wasidentified by Tmin (seconds). The shorter the Tmin, the more efficientthe production of the bottle.

Example 2-1

A polyester was continuously produced by means of a continuouspolymerization apparatus as shown in FIG. 2, which comprises a slurrypreparation tank composed of a single agitation tank, esterificationreaction tanks comprising two agitation tanks connected in series, and atotal of three melt polycondensation reactors comprising an agitationtank and two horizontal plug flow type reactors following it.

To the slurry preparation tank 1, an ethylene glycol solution of ethylacid phosphate (concentration: 0.3 wt %) in such an amount that 9 ppm ofphosphorus atoms would remain per 1 kg of the formed polyester resin,and terephthalic acid and ethylene glycol, were supplied so that theratio of terephthalic acid:ethylene glycol would be 865:485 (weightratio), to obtain a slurry. This slurry was continuously supplied to theesterification reactors. The reaction conditions in the esterificationreactors were such that the first stage 2 was carried out in a nitrogenatmosphere at 260° C. under a relative 2 pressure of 50 KPa (0.5 kg/cmG) for an average retention time of 4 hours, and the second stage 3 wascarried out similarly in a nitrogen atmosphere at 260° C. under 5 KPa(0.05 kg/cm²G) for an average retention time of 1.5 hours.

From an upper pipe installed in the second stage esterification reactor,an ethylene glycol solution of magnesium acetate tetrahydrate(concentration: 0.6 wt %) was continuously supplied in such an amountthat 15 ppm of magnesium atoms would remain per 1 kg of the formedpolyester resin.

In this case, the esterification ratio in the first step esterificationwas 85%, and the esterification ratio in the second stage esterificationwas 95%.

The esterification reaction product was continuously supplied to themelt polycondensation reactors via a conduit 5. At an intermediate pointof the conduit 5, an ethylene glycol solution of tetrabutyl titanate(concentration: 0.2 wt %) in such an amount that 2.0 ppm of titaniumatoms would remain per 1 kg of the formed polyester resin, and anethylene glycol solution of antimony trioxide (concentration: 1.9 wt %)in such an amount that 90 ppm of antimony atoms would remain per 1 kg ofthe formed polyester resin, were continuously added to theesterification reaction product, via a conduit 4.

The reaction conditions in the melt polycondensation reactors were suchthat the first stage was carried out at 270° C. under an absolutepressure of 2.6 KPa (20 Torr) for an average retention time of 1.2hours, the second stage was carried out at 278° C. under an absolutepressure of 0.5 KPa (4 Torr) for an average retention time of 1.2 hours,and the third stage 8 was carried out at 280° C. under an absolutepressure of 0.3 KPa (2 Torr) for an average retention time of 1.2 hours.The melt polycondensation reaction product was extruded from the die inthe form of a strand, cooled and solidified, and then cut by a cutter toobtain melt polymerized chips having an average weight of 24 mg perchip. The intrinsic viscosity of the chips was 0.60 dl/g.

The chips were continuously supplied to a crystallizer maintained atabout 160° C. and having a nitrogen atmosphere and maintained for about60 minutes with stirring. Then, via a preheater, they were continuouslysupplied to a tower type solid polycondensation apparatus and subjectedto a solid phase polycondensation reaction in a nitrogen atmosphere at205° C. With respect to the obtained solid phase polycondensate chips,the amount of antimony eluted, the intrinsic viscosity, thecopolymerized amount of diethylene glycol, the acetaldehyde content, thecarboxylic acid terminal number and the color coordinate value b weremeasured by the above-described methods. Further, the obtained solidphase polycondensate chips were dried at 160° C. for 4 hours in anitrogen stream of 40 l/min in an inert oven (“IPHH-201 model”,manufactured by ESPEC COMPANY). Then, by an injection molding machine(“M-70AII-DM”, manufactured by Meiki Co., Ltd.), a stepped molded platehaving the shape as shown in FIG. 1 and having a size of 50 mm×100 mmand thicknesses of six steps ranging from 6 mm to 3.5 mm in thetransverse direction with each step being 0.5 mm, was injection-moldedat a cylinder temperature of 280° C. under a back pressure of 5×10⁵ Paat an injection rate of 40 cc/sec under a dwell pressure of 35×10⁵ Pa ata mold temperature of 25° C. with a molding cycle of about 75 seconds(in FIG. 1, G indicates a gate portion). With respect to the moldedplate, the acetaldehyde content and the temperature-loweringcrystallization temperature were measured by the above-describedmethods, and the results are shown in Table 3.

Further, the obtained solid phase polycondensate chips were subjected toevaluation for molding of a bottle. The minimum heating time of thepreform at the time of molding was as short as 60 seconds, and it waspossible to obtain the bottle satisfying both transparency and heatresistance, efficiently with a high productivity. The analyzed valuesand the evaluation results are shown in Table 2.

Examples 2-2 to 2-9

Polyester resin chips were obtained in the same manner as in Example 2-1except that catalysts were added so that the amounts of remainingelements derived from the catalysts were as disclosed in Table 1. Theanalytical values and evaluation results of the obtained chips are shownin Table 2.

Comparative Example 2-1

Melt polymerized chips were obtained in the same manner as in Example2-1 except that no ethyl acid phosphate was added to the slurrypreparation tank 1, an ethylene glycol solution of magnesium acetatetetrahydrate was continuously added to the first stage esterification insuch an amount that 27 ppm of magnesium atoms would remain per 1 kg ofthe formed polyester resin, an ethylene glycol solution of phosphoricacid was continuously added to the second stage esterification in suchan amount that 26 ppm of phosphorus atoms would remain per 1 kg of theformed polyester resin, and at an intermediate position of the conduit5, an ethylene glycol solution of antimony trioxide in such an amountthat 81 ppm of antimony atoms would remain per 1 kg of the formedpolyester resin and an ethylene glycol solution of tetrabutyl titanate(concentration: 0.2 wt %) in such an amount that 3 ppm of titanium atomswould remain per 1 kg of the formed polyester resin, were continuouslyadded to the esterification reaction product, via a conduit 4. theintrinsic viscosity of the obtained melt polymerized chips was 0.52dl/g.

The chips were subjected to a solid phase polycondensation reaction inthe same manner as in Example 2-1. The analytical values and evaluationresults of the obtained resin are shown in Table 2. With the resin ofthis example, the intrinsic viscosity was low as compared with Examples,and the values of diethylene glycol, AA, AV and b were high, thusindicating deterioration of both the polymerizability and quality of theproduct. Further, in the evaluation for molding of a bottle, the minimumheating time of the preform at the time of the molding was long at alevel of 70 seconds, thus indicating poor productivity, whereby thebottle cannot be obtained efficiently.

Comparative Example 2-2

A melt polymerized chips were obtained in the same manner as in Example2-1 except that the amount of the ethylene glycol solution of ethyl acidphosphate added to the slurry preparation tank 1 was changed to such anamount that 90 ppm of phosphorus atoms would remain per 1 kg of theformed polyester resin, no magnesium acetate tetrahydrate was added tothe second stage esterification, and at an intermediate point of theconduit 5, the solution having a mixture of magnesium acetatetetrahydrate and antimony trioxide dissolved in ethylene glycol, wascontinuously added to the esterification reaction product, via a conduit4, so that 57 ppm of magnesium atoms and 180 ppm of antimony atoms wouldremain per 1 kg of the formed melt polymerized polyester resin. Theintrinsic viscosity of the obtained melt polymerized chips was 0.58dl/g.

The chips were subjected to a solid phase polycondensation reaction inthe same manner as in Example 2-1. The analytical values and theevaluation results for molding a bottle, of the obtained resin, areshown in Table 2.

Comparative Example 2-3

An ester exchange reaction of 100 parts of dimethyl terephthalate and 70parts of ethylene glycol was initiated in accordance with a usual methodby using, as ester exchange catalysts, calcium acetate monohydrate andmagnesium acetate tetrahydrate, as shown in Table 2. After 20 minutesfrom the initiation of distillation of methanol, antimony trioxide wasadded as shown in Table 2, and the ester exchange reaction wascontinued. Then, trimethyl phosphate was added as shown in Table 2, andthe ester exchange reaction was substantially completed. Further,tetrabutyl titanate was added as shown in Table 2, and then,continuously, polycondensation was carried out in accordance with ausual method at a high temperature under a high vacuum condition, toobtain a polyethylene terephthalate polyester having an intrinsicviscosity of 0.60 (o-chlorophenol, 35° C.).

The chips were subjected to a solid polycondensation reaction in thesame manner as in Example 2-1. The analytical values and the evaluationresults for molding a bottle, of the obtained PET resin, are shown inTable 2. Further, in the evaluation for forming a bottle, even if theheating time of the preform was changed to 70 seconds, it was impossibleto obtain a bottle whereby both transparency and heat resistance areevaluated to be “∘” or “⊚”. Accordingly, the minimum heating time Tmin(seconds) of the preform was indicated as “more than 70 seconds”.

Comparative Example 2-4

Polyester resin chips were obtained in the same manner as in Example 2-1except that the amounts of the copolymerized components and the amountsof remaining atoms derived from the catalysts were as disclosed in Table2. The analytical values and evaluation results for the obtained chips,are shown in Table 2. Further, in the evaluation for molding of abottle, even if the heating time of the preform was changed to 70seconds, it was impossible to obtain a bottle whereby both transparencyand heat resistance are evaluated to be “∘” or “⊚”, and accordingly, theminimum heating time Tmin (seconds) of the preform was indicated as“more than 70 seconds”.

TABLE 2 Examples 2-1 2-2 2-3 2-4 2-5 Amount of Sb eluted 0.16 0.18 0.130.11 0.16 (μg/resin) Sb content (ppm) 90 90 90 90 90 M content (ppm)* 1722 12 7 14 Ti content (ppm) 2 2 2 2 2 Mg content (ppm) 15 20 10 5 12 Pcontent (EAP) 0 0 0 0 0 (ppm) (H3PO4) 9 12 6 3 9 (H3PO3) 0 0 0 0 0 Sb/P(weight ratio) 10.0 7.5 15.0 30.0 10.0 Mg/P (weight ratio) 1.67 1.671.67 1.67 1.33 Production process B B B B B Copolymerized amount 2.2 2.51.9 1.6 2.2 of DEG (mol %) Copolymerized amount 0 0 0 0 0 of IPA (mol %)Physical properties of resin Intrinsic viscosity 0.78 0.78 0.78 0.780.78 (dl/g) Color coordinate b 0.5 0.1 0.9 1.5 0.9 Carboxylic acid 15 2010 35 25 terminal number (AV) (equivalents/ton resin) AAo (ppm) 0.7 0.80.7 0.8 1.5 Quality of molded product 280° C. AAs (ppm) 16.0 16.1 15.413.9 16.5 280° C. ΔAA (ppm) 15.3 15.3 14.7 13.1 15.0Temperature-lowering 167 166 168 169 167 crystallization temperature(Tc₂) (° C.) 270° C. haze (%) 35 — — — — 270° C. AAs (ppm) 12.1 — — — —Bottle Heat resistance/transparency Heating time: 56 sec Δ/◯ X/◯ Δ/◯ Δ/ΔX/◯ 58 sec Δ/◯ Δ/◯ Δ/◯ ◯/Δ Δ/◯ 60 sec ◯/◯ Δ/◯ ◯/◯ ◯/Δ Δ/◯ 62 sec ◯/◯ Δ/◯◯/◯ ◯/◯ Δ/◯ 64 sec ◯/◯ ◯/◯ ◯/◯ ⊚/◯ ◯/◯ 66 sec ⊚/◯ ◯/◯ ⊚/◯ ⊚/◯ ◯/◯ 68 sec⊚/◯ ◯/◯ ⊚/◯ ⊚/◯ ◯/◯ more than ⊚/◯ ⊚/◯ ⊚/◯ ⊚/◯ ⊚/◯ 70 sec Minimum heatingtime 60 64 60 62 64 (sec) sec sec sec sec sec Examples 2-6 2-7 2-8 2-9Amount of Sb eluted 0.14 0.16 0.14 0.29 (μg/resin) Sb content (ppm) 9070 110 150 M content (ppm)* 27 18 16 15.5 Ti content (ppm) 2 3 1 0.5 Mgcontent (ppm) 25 15 15 15 P content (EAP) 0 0 0 0 (ppm) (H3PO4) 9 9 9 9(H3PO3) 0 0 0 0 Sb/P (weight ratio) 10.0 7.8 12.2 16.7 Mg/P (weightratio) 2.78 1.67 1.67 16.7 Production process B B B B Copolymerizedamount 2.3 2.2 2.0 1.9 of DEG (mol %) Copolymerized amount 0 0 0 0 ofIPA (mol %) Physical properties of resin Intrinsic viscosity 0.78 0.780.78 0.78 (dl/g) Color coordinate b 3.1 1.5 0.5 0.9 Carboxylic acid 3515 20 30 terminal number (AV) (equivalents/ton resin) AAo (ppm) 3.2 0.70.8 0.8 Quality of molded product 280° C. AAs (ppm) 17.0 13.4 16.1 15.2280° C. ΔAA (ppm) 13.8 12.7 15.3 14.4 Temperature-lowering 167 165 169173 crystallization temperature (Tc₂) (° C.) 270° C. haze (%) — — — —270° C. AAs (ppm) — — — — Bottle Heat resistance/transparency Heatingtime: 56 sec X/◯ Δ/◯ Δ/Δ Δ/X 58 sec X/◯ Δ/◯ Δ/Δ Δ/X 60 sec X/◯ ◯/◯ Δ/Δ◯/Δ 62 sec X/◯ ◯/◯ ◯/◯ ◯/Δ 64 sec Δ/◯ ◯/◯ ◯/◯ ◯/Δ 66 sec Δ/◯ ⊚/◯ ⊚/◯ ⊚/◯68 sec ◯/◯ ⊚/◯ ⊚/◯ ⊚/◯ more than ◯/◯ ⊚/◯ ⊚/◯ ⊚/◯ 70 sec Minimum heatingtime 68 60 64 68 (sec) sec sec sec sec Comparative Examples 2-1 2-2 2-32-4 Amount of Sb eluted 1.8 1.5 1.2 1.8 (μg/resin) Sb content (ppm) 81180 47 200 M content (ppm)* 29.9 57 119 0 Ti content (ppm) 2.9 0 5 0 Mgcontent (ppm) 27 57 47 0 Ca content (ppm) 0 0 67 0 P content (EAP) 0 900 0 (ppm) (H3PO4) 26 0 0 20 (H3PO3) 0 0 40 0 Sb/P (weight ratio) 3.1 2.01.2 10.0 Mg/P (weight ratio) 1.04 0.63 1.18 0.00 Production process E ED E Copolymerized amount 2.8 2.9 3.5 2.2 of DEG (mol %) Copolymerizedamount 0 0 0 1.8 of IPA (mol %) Physical properties of resin Intrinsicviscosity 0.74 0.78 0.78 0.78 (dl/g) Color coordinate b 1.1 0.1 5.4 1.5Carboxylic acid 45 30 50 30 terminal number (AV) (equivalents/ton resin)AAo (ppm) 3.4 3.1 8.2 2.5 Quality of molded product 280° C. AAs (ppm)24.1 20.8 29.4 23.2 280° C. ΔAA (ppm) 20.7 17.7 21.2 20.7Temperature-lowering 161 162 163 169 crystallization temperature (Tc₂)(° C.) 270° C. haze (%) — 65 — — 270° C. AAs (ppm) — — — — Bottle Heatresistance/transparency Heating time: 56 sec X/◯ X/◯ X/◯ X/Δ 58 sec X/◯X/◯ X/◯ X/Δ 60 sec X/◯ X/◯ X/◯ X/Δ 62 sec X/◯ X/◯ X/◯ X/◯ 64 sec Δ/◯ Δ/◯X/◯ X/◯ 66 sec Δ/◯ Δ/◯ Δ/◯ X/◯ 68 sec Δ/◯ Δ/◯ Δ/◯ Δ/◯ more than ◯/◯ Δ/◯Δ/◯ Δ/◯ 70 sec Minimum heating time 70 70 more more (sec) sec sec than70 than 70 sec sec *M indicates the total of Mg and Ti contents

Examples relating to Polyester {circle around (3)}

Now, Examples for the polyester resin whereby when it is formed into ahollow container for a carbonated beverage, it is possible to obtain thebottle excellent in transparency, strength, taste-deteriorationresistance of the contained beverage, etc. and environmental stresscracking resistance, while suppressing elution of antimony, will bedescribed.

In the Examples of this embodiment, particularly, the following physicalproperties were measured as follows.

Carboxylic Acid Terminal Number (AV)

0.5 g of a resin sample was accurately weighed and dissolved in 25 ml ofbenzyl alcohol at 195° C. and then cooled in ice water. Then, 2 ml ofethyl alcohol was added, and by means of an automatic titrationapparatus (“AUT-301”, manufactured by Toa Denpa K. K.), it wasneutralized and titrated with a 0.01N sodium hydroxide benzyl alcoholsolution. From the measured titration amount A (ml), the blank titrationamount B (ml), the titer F of the 0.01N sodium hydroxide benzyl alcoholsolution and the sample weight W (g), the carboxylic acid terminalnumber (equivalents/ton resin) was calculated by the following formula.

Carboxylic acid terminal number=(A-B)×0.01×F×1,000/W

Temperature-rising Crystallization Temperature (Tc₁) andTemperature-lowering Crystallization Temperature (Tc₂)

The forward end portion (portion A in FIG. 2) in a thickness of 3.5 mmin the molded plate, was cut out and dried at 40° C. for 3 days by avacuum dryer, whereupon a sample cut out from the non-surface portionwas used, and about 10 mg thereof was accurately weighed and sealed inby means of an aluminum oven pan and a pan cover (normal pressure type,“P/N SSC000E030” and “P/N SSC000E032”, manufactured by Seiko Denshi K.K.). By means of a differential scanning calorimeter (“DSC220C”,manufactured by Seiko K. K.), the sample was heated from 20° C. to 285°C. at a rate of 20° C./min in a nitrogen stream, and the crystallizationheat generation peak temperature observed during the temperature rise,was measured and taken as the temperature-rising crystallizationtemperature (Tc₁). Thereafter, it was held in a molten state at 285° C.for 5 minutes and then cooled to 20° C. at a rate of 10° C./min, and thecrystallization heat generation peak temperature observed during thetemperature drop, was measured and taken as the temperature-loweringcrystallization temperature (Tc₂).

Absorbance

A sample cut out from the portion having a thickness of 4 mm (portion Cin FIG. 1) in the molded plate, was measured by means of a double beamspectrophotometer (“U-2000 model”, manufactured by Hitachi, Ltd.) at ascanning speed of 200 nm/min within a range of from 1,100 to 500 nm byABS mode, whereby the value at 1,000 nm was taken as the absorbance.

Haze

With respect to the portion having a thickness of 5 mm (portion C inFIG. 1) in the molded plate, the haze was measured by a haze meter(“NDH-300A”, manufactured by NIPPON DENSHOKU INDUSTRIES CO., LTD.).

Environmental Stress Rupture Time

An injection-molded sheet having a length of 50 mm, a width of 6 mm anda thickness of 1 mm, was immersed in a 0.2 wt % sodium hydroxide aqueoussolution at 25° C. in such a state that it is fixed along the outercircumference of a cylinder having a diameter of 32 mm so that both endsin the length direction of the molded plate extend over a halfcircumference of the outer circumference of the cylinder, whereby thetime until rupture takes place, was measured. The test was repeated fivetimes, and the maximum value and the minimum value were discarded, andan average value of the remaining three tests was taken.

Environmental Stress Cracking Resistance of a Bottle

To 18.8 g of citric acid monohydrate, distilled water adjusted to 0° C.was added to dissolve the citric acid.

Then, the entire amount of this aqueous solution was filled in a bottle,and 22.5 g of sodium bicarbonate was further introduced, whereupon itwas immediately tightly sealed, followed by shaking for a few tensminutes to dissolve sodium bicarbonate. At that time, the interior ofthe bottle corresponds to a state where about 40 times by volume ofcarbon dioxide gas was filled at 0° C. under 1 atm. Then, this filledbottle was left to stand for one day. Thereafter, about ⅓ of the lowerportion was immersed in a 0.2 wt % sodium hydroxide aqueous solution,whereby leakage of the gas from the bottom was visually observed, andthe time until leakage of gas started was relatively compared andevaluated by ○→∘→Δ→X i.e. in the sequential order from one which tookthe longest time.

Example 3-1

13 kg of high purity terephthalic acid having an average particle sizeof 120 μm and a slurry of 5.21 kg of ethylene glycol were sequentiallysupplied over a period of 1.5 hours to an esterification reactormaintained at a temperature of 265° C. under a pressure of 1.5×10⁵ Paand having 0.3 kg of bis(2-hydroxyethyl)terephthalate preliminarilycharged. After completion of the supply, the esterification reaction wascarried out for further 0.5 hour. One half of this esterificationreaction product was transferred to a polycondesation tank. Further,water formed during the esterification reaction was distilled out of thesystem, and the ethylene glycol component was recycled to the system.

Then, to the above polycondensation tank to which the esterificationreaction product was transferred, an ethylene glycol solution of ethylacid phosphate, an ethylene glycol solution of tetrabutoxy titanate, anethylene glycol solution of antimony trioxide and a water/ethyleneglycol solution of magnesium acetate tetrahydrate, were sequentiallyadded with intervals of fiver minutes from a pipe in such amounts that12 ppm of phosphorus atoms (P), 1.8 ppm of titanium atoms (Ti), 120 ppmof antimony atoms (Sb) and 12 ppm of magnesium atoms (Mg) would remainbased on the formed polyester resin, whereupon the interior of thesystem was gradually heated from 250° C. to 278° C., and at the sametime the pressure was reduced from atmospheric pressure to 67 Pa, andwhile maintaining the pressure, the reaction was carried out for 3hours. The formed polymer was withdrawn in the form of a strand from anoutlet formed at the bottom of the polycondensation tank, cooled withice and cut by a cutter into chips, to obtain polyester resin chips.

Then, the polyester resin chips thus obtained were continuously suppliedto an agitation crystallyzer (manufactured by Bepex Company) maintainedat 150° C., and crystallized, then transferred to a stationary solidphase polymerization tower, dried at about 140° C. for 3 hours in anitrogen gas stream of 20 l/kg·hr and then solid phase polycondensed at210° C. for 20 hours.

With respect to the obtained polyester resin chips, the amount ofantimony eluted, the proportion of sophthalic acid as the dicarboxylicacid component in he total dicarboxylic acid component, the proportionof diethylene glycol as a diol component in the total diol component,the carboxylic acid terminal amount, the contents of metal atoms of therespective metal compounds, the aldehyde content and the intrinsicviscosity, were measured by the above-described methods, and the resultsare shown in Table 3.

Further, the obtained polyester resin chips were dried at 160° C. for 4hours in a nitrogen stream of 40 l/min in an inert oven (“IPHH-201model”, manufactured by ESPEC COMPANY). Then, by an injection moldingmachine (“M-70AII-DM”, manufactured by Meiki Co., Ltd.), a steppedmolded plate having the shape shown in FIG. 1 and having a size of 50mm×100 mm and having thicknesses of six steps ranging from 6 mm to 3.5mm in a transverse direction with each step being 0.5 mm, wasinjection-molded at a cylinder temperature of 280° C. under a backpressure of 5×10⁵ Pa at an injection rate of 40 cc/sec under a dwellpressure of 35×10⁵ Pa at a mold temperature of 25° C. with a moldingcycle of about 75 seconds (In FIG. 1, G indicates a gate portion). Withrespect to the obtained molded plate, the temperature-risingcrystallization temperature and the temperature-lowering crystallizationtemperature, the acetaldehyde content, the absorbance and the haze as anindex for transparency, were measured by the above-described methods,and the results are shown in Table 3.

Further, the obtained polyester resin chips were dried at 160° C. for 4hours in a nitrogen stream of 40 l/min in an inert oven (“IPHH-201model”, manufactured by ESPEC COMPANY). Then, by an injection moldingmachine (“MINIMAT 8/7A”, manufactured by Sumitomo Heavy Industries,Ltd.), a molded plate having a length of 50 mm, a width of 6 mm and athickness of 1 mm, was injection-molded at a cylinder temperature of280° C. under a back pressure of 3×10⁵ Pa at an injection rate of 3cc/sec under a dwell pressure of 20×10⁵ Pa at a mold temperature of 20°C. With respect to the obtained molded plate, the environmental stressrupture time was measured by the above-described method, and the resultsare shown in Table 3.

Further, the obtained polyester resin chips were dried at 130° C. for 10hours by a vacuum dryer. Then, by an injection molding machine(“FE-80S”, manufactured by Nissei Plastic Industrial Co., Ltd.), apreform of a test tube shape having an outer diameter of about 29 mm, aheight of about 165 mm, an average wall thickness of about 3.7 mm and aweight of about 60 g, was injection-molded at a cylinder temperature of280° C. under a back pressure of 5×10⁵ Pa at an injection rate of 45cc/sec under a dwell pressure of 30×10⁵ Pa at a mold temperature of 20°C. with a molding cycle of about 40 seconds. The obtained preform washeated for 70 seconds in a near infrared ray irradiation furnaceequipped with a quartz heater, left to cool at room temperature for 25seconds and then introduced into a blow mold set at 40° C. and subjectedto blow molding for 40 seconds under a blow pressure of 7×10⁵ Pa for onesecond and further under a blow pressure of 30×10⁵ Pa for 40 seconds,while stretching in the height direction by a stretching rod, to form abottle having an outer diameter of about 95 mm, a height of about 305mm, an average wall thickness at 10 the body portion of about 0.37 mm, aweight of about 60 g and an internal capacity of about 1.5 l. Withrespect to the obtained bottle, the environmental stress crackingresistance was evaluated by the above-described method, and the resultsare shown in Table 3.

Example 3-2

Polyester resin chips were produced in the same manner as in Example 3-1except that 0.229 g of iron tetraoxide (“HR-370H”, manufactured by TodaKogyo Corp.) was added following the addition of the metal compound atthe time of polycondensation. The obtained polyester resin was measuredand evaluated, and the results are shown in Table 3.

Example 3-3

Polyester resin chips were produced in the same manner as in Example 3-2except that 12.8 kg of terephthalic acid and 0.2 kg of isophthalic acidwere used. The obtained polyester resin was measured and evaluated, andthe results are shown in Table 3.

Comparative Example 3-1

13 kg of high purity terephthalic acid having an average particle sizeof 120 μm and a slurry of 12.2 kg of ethylene glycol were sequentiallysupplied over a period of 4 hours to an esterification reaction tankmaintained at a temperature of 250° C. under a pressure of 1.0×10⁵ Paand having 0.3 kg of bis(2-hydroxyethyl)terephthalate preliminarilycharged. After completion of the supply, the esterification reaction wascarried out for further one hour. One half of this esterificationreaction product was transferred to a polycondensation tank. Further,water formed during the esterification reaction and the ethylene glycolcomponent were distilled in the entire amounts out of the system.

Then, to the above polycondensation tank to which the esterificationreaction product was transferred, from its pipe, an ethylene glycolsolution of ethyl acid phosphate and an ethylene glycol solution ofantimony trioxide were sequentially added with intervals of 5 minutes insuch amounts that 12 ppm of phosphorus atoms (P) and 240 ppm of antimonyatoms (Sb) would remain based on the formed polyester resin. Then, theinterior of the system was gradually heated from 250 to 278° C., and atthe same time, the pressure was reduced from atmospheric pressure to 67Pa, and while maintaining the same pressure, the reaction was carriedout for 3 hours. The formed polymer was withdrawn in the form of astrand from an outlet formed at the bottom of the polycondensation tank,cooled with water and then cut by a cutter into chips, to obtainpolyester resin chips. Thereafter, solid phase polycondensation wascarried out in the same manner as in Example 3-1. Then, the obtainedpolyester resin was measured and evaluated, and the results are shown inTable 3.

Comparative Example 3-2

Polyester resin chips were produced in the same manner as in ComparativeExample 3-1 except that 110 g of ethylene glycol was added following theaddition of the metal compound during polycondensation. The obtainedpolyester resin was measured and evaluated, and the results are shown inTable 3.

Comparative Example 3-3

13 kg of high purity terephthalic acid having an average particle sizeof 50 μm and a slurry of 12.2 kg of ethylene glycol, were sequentiallysupplied over a period of 3.5 hours to an esterification reactormaintained at a temperature of 250° C. under a pressure of 1.0×10⁵ Paand having 0.3 kg of bis(2-hydroxyethyl)terephthalate preliminarilycharged. After completion of the supply, the esterification reaction wascarried out for further one hour. One half of this esterificationreaction product was transferred to the polycondensation tank.

Further, water formed during the esterification reaction and theethylene glycol component were distilled in their entire amount out ofthe system.

Then, to the above polycondensation tank to which the esterificationreaction product was transferred, from its pipe, an ethylene glycolsolution of ethyl acid phosphate, an ethylene glycol solution ofantimony trioxide and a water/ethylene glycol solution of magnesiumacetate tetrahydrate, were sequentially added with intervals of 5minutes in such amounts that 17 ppm of phosphorus atoms (P), 240 ppm ofantimony atoms (Sb) and 15 ppm of magnesium atoms (Mg) would remainbased on the formed polyester resin, whereupon the interior of thesystem as gradually heated from 250° C. to 278° C., and at the sametime, the pressure was reduced from atmospheric pressure to 67 Pa, andwhile maintaining the same pressure, the reaction was carried out for 3hours. The formed polymer was withdrawn in the form of a strand from anoutlet formed at the bottom of the polycondensation tank, cooled withwater and then cut by a cutter into chips, to obtain polyester resinchips. Thereafter, solid phase polycondensation was carried out in thesame manner as in Example 3-1. Then, the obtained polyester resin wasmeasured and evaluated, and the results are shown in Table 3.

TABLE 3 Examples 3-1 3-2 3-3 Amount of Sb eluted 0.19 0.19 0.27(μg/resin) Sb content (ppm) 120 120 120 Ti content (ppm) 1.8 1.8 1.8 Mgcontent (ppm) 12 12 12 P content (EAP) (ppm) 12 12 12 (100 × Ti + Sb)(ppm) 300 300 300 Sb/P (weight ratio) 10.00 10.00 10.00 Mg/P (weightratio) 1.00 1.00 1.00 Production process C C C Copolymerized amount ofDEG 1.5 1.5 1.5 (mol %) Copolymerized amount of IPA 0 0 1.5 (mol %)Physical properties of resin Intrinsic 0.86 0.86 0.88 viscosity (dl/g)Carboxylic acid 30 32 31 terminal number (AV) (equivalents/ton resin)AAo (ppm) 2.5 2.3 2.4 Quality of molded product 280° C. AAs (ppm) 14.814.4 14.5 280° C. ΔAA (ppm) 12.3 12.1 12.1 Temperature- 162 162 172rising crystallization temperature (Tc₁) (° C.) Temperature- 174 174 162lowering crystallization temperature (Tc₂) (° C.) 280° C. haze (%) 6 149 270° C. haze (%) — — 5 270° C. AAs (ppm) — — 11.2 Environmental 17 1614 stress rupture time (min) Absorbance 0.04 0.09 0.08 BottleEnvironmental ◯ ⊚ ⊚ stress cracking resistance Comparative Examples 3-13-2 3-3 Amount of Sb eluted 2.0 2.0 2.0 (μg/resin) Sb content (ppm) 240240 240 Ti content (ppm) 0 0 0 Mg content (ppm) 0 0 15 P content (EAP)(ppm) 12 12 17 (100 × Ti + Sb) (ppm) 240 240 240 Sb/P (weight ratio)20.0 20.0 14.12 Mg/P (weight ratio) 0.00 0.00 0.88 Production process EE E Copolymerized amount of DEG 2.5 3.5 2.0 (mol %) Copolymerized amountof IPA 0 0 0 (mol %) Physical properties of resin Intrinsic 0.83 0.880.87 viscosity (dl/g) Carboxylic acid 20 22 18 terminal number (AV)(equivalents/ton resin) AAo (ppm) 2.7 2.6 2.7 Quality of molded product280° C. AAs (ppm) 20.6 21.6 26.1 280° C. ΔAA (ppm) 17.9 19.0 23.4Temperature- 149 167 147 rising crystallization temperature (Tc₁) (° C.)Temperature- 182 167 188 lowering crystallization temperature (Tc₂) (°C.) 280° C. haze (%) 20 2 35 270° C. haze (%) 65 — — 270° C. AAs (ppm) —— — Environmental 7 4 8 stress rupture time (min) Absorbance 0.06 0.060.06 Bottle Environmental X X Δ stress cracking resistance

Examples Relating to Polyester {circle around (4)}

Examples for the polyester resin whereby particularly when it is formedinto a hollow container to be used by heat sterilization filling, it ispossible to obtain a bottle of which the transparency of the bodyportion will not deteriorate, which is excellent in productivity of ahollow container as the crystallization rate at the mouth stopperportion is high and which is excellent in the dimensional stability ofthe mouth stopper portion whereby deformation at the mouth stopperportion at the time of heat sterilization filling is little, whilesuppressing elution of antimony, will be described.

Further, in the Examples of this embodiment, particularly, the followingphysical properties were measured as follows.

Proportion of Ethylene Terephthalate Units in the Polyester Resin

Using a 3 wt % solution having a resin sample dissolved in deuteratedtrifluoroacetic acid at room temperature, 1H-NMR was measured by anuclear magnetic resonance apparatus (“JNM-EX270 model”, manufactured byJEOL. Ltd). The respective peaks were identified, and from theirintegral ratios, dicarboxylic acid components other than terephthalicacid, and diol components other than ethylene glycol were calculated,whereby the proportion of ethylene terephthalate units was obtained.

The Temperature-rising Crystallization Temperature (Tc1) and theTemperature-lowering Crystallization Temperature (Tc2)

The forward end portion (portion A in FIG. 1) in a thickness of 3.5 mmin the molded plate, was cut out and dried at 40° C. for 3 days by avacuum dryer, whereupon a sample cut out from the non-surface portionwas used, and about 10 mg thereof was accurately weighed and sealed inby means of an aluminum oven pan and a pan cover (normal pressure type,“P/N SSC000E030” and “P/N SSC000E032”, manufactured by Seiko Denshi K.K.). By means of a differential scanning calorimeter (“DSC220C”,manufactured by Seiko K. K.), the sample was heated from 20° C. to 285°C. at a rate of 20° C./min in a nitrogen stream, and the crystallizationheat generation peak temperature observed during the temperature rise,was measured and taken as the temperature-rising crystallizationtemperature (Tc₁). Thereafter, it was held in a molten state at 285° C.for 5 minutes and then cooled to 20° C. at a rate of 10° C./min, and thecrystallization heat generation peak temperature observed during thetemperature drop, was measured and taken as the temperature-loweringcrystallization temperature (Tc₂).

Example 4-1

40 kg of terephthalic acid and a slurry of 16.1 kg of ethylene glycolwere sequentially supplied over 4 hours to an esterification reactormaintained at a temperature of 250° C. under a pressure of 1.2×10⁵ Paand having about 50 kg of bis(2-hydroxyethyl)terephthalate preliminarilycharged, and after completion of the supply, the esterification reactionwas carried out for further one hour. 50 kg of this esterificationreaction product was transferred to a polycondensation tank.

Then, to the above polycondensation tank to which the esterificationreaction product was transferred, from its pipe, an ethylene glycolsolution of ethyl acid phosphate, a water/ethylene glycol solution ofmagnesium acetate and antimony trioxide, and an ethylene glycol solutionof tetra-n-butoxy titanium, were sequentially added with intervals of 5minutes so that 0.420 mol of phosphorus atoms (P), 0.700 mol ofmagnesium atoms (Mg), 0.986 mol of antimony atoms (Sb) and 0.021 mol oftitanium atoms (Ti) would remain per 1 ton of the polyester resin. Then,further, 582 g of diethylene glycol, a low density polyethylene resin(“UE320”, manufactured by Japan Polychem Corporation) were added so thatit would be 0.040 ppm based on the weight of the polyester resin.Thereafter, the interior of the system was heated from 250° C. to 280°C. over a period of two hours and 30 minutes, and the pressure wasreduced from atmospheric pressure to 400 Pa over a period of one hourand then maintained at the same pressure. Melt polycondensation wascarried out for a period of time until the intrinsic viscosity of theobtainable resin became 0.62 dl/g, and the polymer was withdrawn in theform of a strand from an outlet provided at the bottom of thepolycondensation tank, cooled with water and then cut by a cutter intochips to obtain about 40 kg of polyethylene terephthalate resin(copolymerized amount of diethylene glycol: 3.4 mol %).

Then, the polyester resin chips thus obtained were continuously suppliedto an agitation crystallizer (manufactured by Bepex Company) maintainedat about 160° C. so that the retention time would be about 5 minutes,crystallized and then dried at 160° C. for 4 hours in a nitrogen streamof 40 l/min in an inert oven (“IPHH-201 model”, manufactured by ESPECCOMPANY), and then heated at 210° C. for a period of time until theintrinsic viscosity became 0.839 dl/g, for solid polycondensation.

With respect to the obtained polyester resin chips, the amount ofantimony eluted, the contents of metal atoms derived from the respectivemetal compounds, the intrinsic viscosity, as well as the acetaldehydecontent and color coordinate b as the color tone, were measured, and theresults are shown in Table 4.

Further, the obtained polyester resin composition chips were dried at160° C. for 4 hours in a nitrogen stream of 40 l/min in an inert oven(“IPHH-201 model”, manufactured by ESPEC COMPANY). Then, by an injectionmolding machine (“M-70AII-DM”, manufactured by Meiki Co., Ltd.), astepped molded plate having the shape as shown in FIG. 1 and having asize of 50 mm×100 mm and thicknesses of six steps ranging from 6 mm to3.5 mm in a transverse direction with each step being 0.5 mm, wasinjection-molded at a cylinder temperature of 280° C. under a backpressure of 5×10⁵ Pa at an injection rate of 40 cc/sec under a dwellpressure of 35×10⁵ Pa at a mold temperature of 25° C. with a moldingcycle of about 75 seconds (in FIG. 1, G indicates a gate portion). Withrespect to the obtained molded plate, the cyclic trimer content, theacetaldehyde content, the temperature-rising crystallization temperatureand the temperature-lowering crystallization temperature, and the hazeas an index for transparency, were measured by the above-describedmethods, and the results are shown in Table 4.

Further, the obtained polyester resin composition chips were dried at130° C. for 10 hours in a vacuum dryer. Then, by an injection moldingmachine (“FE-80S”, manufactured by Nissei Plastic Industrial Co., Ltd.),a preform of a test tube shape having an outer diameter of about 29 mm,a height of about 165 mm, an average wall thickness of about 3.7 mm anda weight of about 60 g, was injection-molded at a cylinder temperatureof 280° C. under a back pressure of 5×10⁵ Pa at an injection rate of 45cc/sec under a dwell pressure of 30×10⁵ Pa at a mold temperature of 20°C. with a molding cycle of about 40 seconds. The mouth stopper portionof the obtained preform was heated for from 150 to 180 seconds by aquartz heater type mouth stopper portion crystallizer, and then a moldpin was inserted to carry out crystallization treatment of the mouthstopper portion, and the shape and dimension of the mouth stopperportion at that time were visually observed and evaluated in accordancewith the following standards, and the results are shown in Table 4.

Shape and dimension of the mouth stopper portion

⊚: constant dimensional precision was obtained.

X: crystallization was inadequate and a distortion was observed in theshape.

Then, the preform having the mouth stopper portion subjected tocrystallization treatment, was heated for 70 seconds in a near infraredray irradiation furnace equipped with a quartz heater, left at roomtemperature for 25 seconds and then introduced into a blow mold set at160° C., followed by blow molding under a blow pressure of 7×10⁵ Pa forone second and further under a blow pressure of 30×10⁵ Pa for 40seconds, while stretching in the height direction by a stretching rod,heat set and then cooled in air to form a bottle having an outerdiameter of about 95 mm, a height of about 305 mm, an average wallthickness of the body portion of about 0.37 mm, a weight of about 60 g,an internal capacity of about 1.5 l and a specific surface area of about0.7 cm⁻¹. With respect to the obtained bottle, the appearance wasvisually observed and evaluated in accordance with the followingstandards, and further, the amount of the antimony compound eluted byhot water was measured by the above-described method, and the resultsare shown in Table 4.

Appearance of the Bottle

⊚: transparency was excellent, and it was good as a whole.

∘: transparency was good, it was good as a whole.

X: blackening or whitening observed, and transparency was poor.

Example 4-2

A polyester resin was produced in the same manner as in Example 4-1except that no low density polyethylene resin was added at the time ofmelt polycondensation, and with respect to the polyester resin, theamount of antimony eluted, the proportion of ethylene terephthalateunits, the contents of metal atoms, the intrinsic viscosity, as well asthe amount of antimony eluted, the cyclic trimer content, theacetaldehyde content, and the color tone, were measured. Further, instepped molded plate was injection-molded, and the cyclic trimercontent, the acetaldehyde content, the temperature-risingcrystallization temperature and the temperature-lowering crystallizationtemperature, and the transparency, were measured. Further, a bottle wasformed by injection blow molding, and the shape of the mouth stopperportion and the appearance of the bottle were evaluated, and the amountof antimony eluted was measured. The results are shown in Table 4.

Example 4-3

A polyester resin was produced in the same manner as in Example 4-1except that the low density polyethylene resin was added so that itwould be 1,500 ppm based on the weight of the polyester resin, at thetime of melt polycondensation. With respect to the polyester resin, theamount of antimony eluted, the proportion of ethylene terephthalateunits, the contents of metal atoms, the intrinsic viscosity, as well asthe amount of antimony eluted, cyclic trimer content, the acetaldehydecontent and the color tone, were measured. Further, a stepped moldedplate was injection-molded, and the cyclic trimer content, theacetaldehyde content, the temperature-rising crystallization temperatureand the temperature-lowering crystallization temperature, and thetransparency, were measured. Further, a bottle was formed by injectionblow molding, and the shape of the mouth stopper portion and theappearance of the bottle, were evaluated, and the amount of antimonyeluted was measured. The results are shown in Table 4.

Comparative Example 4-1

A polyester resin composition was produced in the same manner as inExample 4-1 except that at the time of melt polycondensation,orthophosphoric acid was used as the phosphorus compound, and theamounts of the phosphorus acid, antimony trioxide and magnesium acetatewere changed, and no tetra-n-butoxy titanium was added, and nodiethylene glycol or no low density polyethylene resin was added. Withrespect to the polyester resin, the proportion of ethylene terephthalateunits, the contents of metal atoms, the intrinsic viscosity as well asthe amount of antimony eluted, the cyclic trimer content, theacetaldehyde content and the color tone, were measured. Further, astepped molded plate was injection-molded, and the cyclic trimercontent, the acetaldehyde content, the temperature-risingcrystallization temperature and the temperature-lowering crystallizationtemperature, and the transparency, were measured. Further, a bottle wasformed by injection blow molding, and the shape of the mouth stopperportion and the appearance of the bottle were evaluated, and the amountof antimony eluted, was measured. The results are shown in Table 4.

TABLE 4 Comparative Examples Example 4-1 4-2 4-3 4-1 Amount of Sb eluted0.23 0.23 0.23 2.2 (μg/resin) Sb content (ppm) 110 110 109 269 Ticontent (ppm) 1 1 1 0 Mg content (ppm) 17 17 17 15 P content (EAP) 13 1313 15 Sb/P (weight ratio) 8.45 8.46 8.38 17.93 Mg/P (weight ratio) 1.311.31 1.31 1.00 Production process C C C E Copolymerized amount of 3.4 ≦5≦5 ≦3 DEG (mol %) Physical properties of resin Intrinsic 0.839 0.8200.830 0.840 viscosity (dl/g) Cyclic trimer 0.30 0.31 0.31 0.31 content(CT₀) (wt %) Color coordinate 2.1 2.2 1.9 2.1 b Polyolefin 0.040 0 15000 content (ppb) AAo (ppm) 1.5 1.5 1.5 2.4 Quality of molded product 280°C. AAs (ppm) 19.9 20.2 19.8 22.5 280° C. ΔAA (ppm) 18.4 18.7 18.3 20.1280° C. CTs (wt %) 0.40 0.42 0.41 0.42 280° C. ΔCT (wt %) 0.10 0.11 0.100.11 Temperature- 162.0 166.7 149.0 155.5 rising crystallizationtemperature (Tc₁) (° C.) Temperature- 176.3 176.8 185.2 190.2 loweringcrystallization temperature (Tc₂) (° C.) 280° C. haze (%) 4.1 4.2 35.536.5 270° C. haze (%) 5 — — 85 270° C. AAs (ppm) 13.4 — — 15.2 270° C.CTs (wt %) 0.35 — — 0.36 Bottle Amount of Sb 0.8 0.8 0.8 1.1 eluted(ppb) Shape and ◯ X ◯ ◯ dimension of mouth stopper portion Appearance of⊚ ⊚ X X bottle

Examples Relating to Polyester {circle around (5)}

Now, it will be shown that the polyester resin of the present inventioncan be molded without losing transparency even when the moldingtemperature is set to be lower than ever, whereby formation ofacetaldehyde during the molding and contamination of the mold during themolding can be suppressed, and it is possible to obtain a molded productexcellent also in transparency, and it is thus suitable for a hollowcontainer.

Namely, the following evaluations were carried out in Examples 1-1, 1-9,2-1, 3-3 and 4-1, and Comparative Examples 1-2, 2-2 and 3-1, and theresults are shown in Tables 1, 2, 3 and 4.

Namely, a resin obtained in each Example was dried at 160° C. for 16hours in a vacuum dryer (“DP-41 model”, manufactured by YAMATOSCIENTIFIC CO., LTD.). Then, by an injection molding machine(“M-70AII-DM”, manufactured by Meiki Co., Ltd.), a stepped molded platehaving the shape shown in FIG. 1 and having a size of 50 mm×100 mm andthicknesses of six steps ranging from 6 mm to 3.5 mm in a transversedirection with each step being 0.5 mm, was injection-molded at acylinder temperature of 270° C. under a back pressure of 5×10⁵ Pa at aninjection rate of 40 cc/sec under a dwell pressure of 35×10⁵ Pa at amold temperature of 25° C. with a molding cycle of about 75 seconds.Further, in FIG. 1, G indicates a gate portion.

With respect to the molded plate, the haze, the acetaldehyde content(AA_(s)) and the cyclic trimer content (CT_(s)) were measured by thefollowing methods, and the results are shown in Table 1.

270° C. Haze

With respect to the portion having a thickness of 5.0 mm (portion C inFIG. 1) in the molded plate, the haze was measured by means of a hazemeter (“NDH-300A”, manufactured by NIPPON DENSHOKU INDUSTRIES CO.,LTD.).

Acetaldehyde (270° C. AA_(s))

A chip of 4×4 mm was cut out from the rear end portion having athickness of 3.5 mm (portion B in FIG. 1) in the molded plate, and usingthe chip as a sample, it was measured by the same method as describedabove.

Cyclic Trimer Content (270° C. CT_(s))

Using a sample cut out from the forward end portion having a thicknessof 3.5 mm (portion A in FIG. 1) in the molded plate, it was measured bythe same method as described above.

Examples Relating to Polyester {circle around (6)}

Now, Examples for the polyester resin whereby the number of particles inthe interior of the resin can be minimized so that thread breakage orfilm rupture caused by such particles will not substantially occur atthe time of molding fibers or films, and projections such as fish eyeswill not substantially form on the surface, when it is formed into amolded product such as a film or bottle, will be described.

In the Examples of this embodiment, particularly the following physicalproperties were measured as follows.

Number of Particles in the Interior of the Resin

10 kg of a sample resin was subjected to crystallization and drying ofchips in a hot air dryer at 180° C. for two hours, whereby the moisturein the chips became not more than 100 ppm. This resin was extruded by a40 mmφ single screw extruder at a resin temperature of 285° C. at anextrusion rate of 8 kg/hr while filtering by means of a metal fibersintered filter (95% cut filtration precision: 15 μm), and by tubularmolding, a non-stretched film having a thickness of 210 μm and width of10 cm was obtained. At that time, the extruder die was a 4-threadedspiral die of 80 mmφ, and the cooling ring was one equipped with a 60mmφ internal water-cooling jacket.

The obtained film was peeled along the bonded face at the time of thetubular molding to expose an immaculate surface, which is used as asample for microscopic examination.

A CCD camera is mounted on a trinocular head of a phase contrastmicroscope (OPTIPHOT XF-Ph model, manufactured by Nikon Corporation,objective lens: 40X), and by means thereof, a variable-density imageswill be input to an image treating apparatus (SPICCA-II model,manufactured by Nippon Avionics Co., Ltd.). In the case of thisconstruction, on the display, the magnification is about 1,000 times,and the visual field is 0.123 mm×0.114 mm.

The measuring operation was carried out as follows.

The focus was adjusted on the front side and the rear side of a filmsample, to confirm the range of the film thickness. Then, while carryingfocal scanning from the front side to the rear side in an accumulableinput mode of variable-density images by an image treating apparatus,the images are taken in, and particles having an absolute maximum length(*) of at least 1 μm, were counted.

This operation was repeated three times at different visual fields, andthe average number thereof was calculated per 0.01 mm³ of the filmvolume and taken as “the number of particles having a long diameter ofat least 1 μm in the interior of the resin”.

* “Absolute maximum length”: The length corresponding to the maximumdistance between optional two points on the circumference of an object(a particle) detected by the image treating apparatus.

Quantitative Analysis of the Diethylene Glycol Component

50 ml of a 4N-KOH/methanol solution was added to 5.00 g of a sampleresin pulverized by a Willette type pulverizer (model: 1029-A)manufactured by Yoshida Co., Ltd. by means of a perforated plate having1.5 mm holes, and a reflux condenser was set. Then, it was heated andrefluxed for hydrolysis for two hours while stirring on a hot plate(surface temperature: 200° C.) equipped with a magnetic stirrer. Aftercooling, about 20 g of high purity terephthalic acid was added, followedby shaking thoroughly for neutralization to obtain a slurry having a pHof not higher than 9, which was filtered by means of a 11G-4 glassfilter and then washed twice with 2 ml of methanol. The filtrate and thewashing liquids were put together to obtain a sample liquid for gaschromatography. By a microsyringe, 1 μl of the sample liquid wasinjected to a gas chromatography of Shimadzu Corporation (model:GC-14APF), and from the areas of peaks, mol % of a diethylene glycolcomponent based on the total glycol component was calculated inaccordance with the following formula.

mol % of the diethylene glycol component=(ACO×CfCO)/(Σ(A×Cf))×100

ACO: area of the diethylene glycol component (μV·sec)

CfCO: correction coefficient of the diethylene glycol component

A: area of each glycol component (μV·sec)

Cf: correction coefficient of each glycol component

The conditions for using the gas chromatography were as follows.

Column: “DB-WAX”, manufactured by J&W (0.53 mm × 30 m) Set temperatures:Column: 160° C. to 220° C. Vaporizing chamber: 230° C. Detector: 230° C.Gas flow rates: Carrier (nitrogen): 5 ml/min Hydrogen: 0.6 kg/cm² Air:0.6 kg/cm² Detector: FID Sensitivity 102 MΩ

Quantitative Analysis of Carboxylic Acid Terminal Number

Chips were pulverized, then dried at 140° C. for 15 minutes by a hot airdrier and cooled to room temperature in a desiccator to obtain a sample.From this sample, 0.1 g was accurately weighed and put into a test tubeand after an addition of 3 ml of benzyl alcohol, dissolved at 195° C.for 3 minutes while blowing dry nitrogen gas thereto. Then, 5 ml ofchloroform was gradually added, followed by cooling to room temperature.To this solution, a phenol red indicator was added in an amount of oneor two drops, followed by titration with a 0.1N sodium hydroxide benzylalcohol solution with stirring while blowing dry nitrogen gas thereto.The titration was terminated at a time point where the color changedfrom yellow to red. Further, as a blank, the same operation was carriedout without using the polyester resin sample, and the acid number wascalculated by the following formula.

Acid number (mol/ton)=(A-B)×0.1×f/W [where A is the amount (μl) of the0.1N sodium hydroxide benzyl alcohol solution required for thetitration, B is the amount (μl) of the 0.1N sodium hydroxide benzylalcohol solution required for the titration of the blank, W is theamount (g) of the polyester resin sample, and f is the titer of the 0.1Nsodium hydroxide benzyl alcohol solution.]

For the titer (f) of the 0.1N sodium hydroxide benzyl alcohol solution,5 ml of methanol was taken into a test tube and, after adding an ethanolsolution of phenol red as an indicator in an amount of one or two drops,titration was carried out to the point of color change with 0.4 ml ofthe 0.1N sodium hydroxide benzyl alcohol solution. Then, 0.2 ml of a0.1N hydrochloric acid aqueous solution having a known titer was addedas a standard solution, followed by titration against the point of colorchange with the 0.1N sodium hydroxide benzyl alcohol solution. (theforegoing operation was carried out while blowing dry nitrogen gasthereto.) The titer (f) was calculated by the following formula.

Titer (f)=titer of the 0.1N hydrochloric acid aqueous solution×amount(μl) of the 0.1N hydrochloric acid aqueous solution/titrated amount (μl)of the 0.1N sodium hydroxide benzyl alcohol solution

Volume Resistivity

Into a branched test tube having an inner diameter of 20 mm and a lengthof 18 cm, 15 g of a sample was put, after thoroughly replacing theinterior of the system with nitrogen, this test tube was immersed in anoil bath of 160° C., and by means of a vacuum pump, inside of the tubewas brought to not more than 1 Torr and vacuum-dried for 4 hours. Then,the temperature of the bath was raised to 285° C. to melt the sample.Then, nitrogen supply and vacuuming were repeated to remove thecontained air babbles. Then, in this melt, stainless steel electrodes(two sheets of stainless steel electrodes having an area of 1 cm²disposed in parallel with a distance of 5 mm, and the rear sides notfacing, were covered with an insulating material) were inserted. Afterthe temperature was sufficiently stabilized, 100V of direct currentvoltage was applied by a high resistance meter (MODEL HP4329A),manufactured by Hewlett-Packard Company, and the resistance at the timeof the application was taken as the volume resistivity (Ω·cm).

Evaluation of Forming a Film

In the same method as the method disclosed in the section for the methodfor measurement the number of particles in the interior of the resin, anon-stretched film was prepared by tubular extrusion.

The obtained non-stretched film was subjected to stretching and heatsetting under the following conditions by a biaxial stretching machinemanufactured by T.M. Long Company, to obtain a biaxially stretched film.

Preheating and heat setting temperature: 92° C.

Preheating time: 2 minutes

Stretching ratio: 4.0 times×3.5 times

Stretching rate: 20,000%/min (3,000 cm/min)

Stretching method: simultaneous biaxial stretching

Heat setting time: 1 minute

The obtained biaxially stretched film was bonded to a square metal framemade of SUS, and aluminum was vapor deposited on the film surface in avacuum vapor deposition machine. Then, on its surface, a frame of 2cm×2.5 cm was marked at random, and the number of coarse projections inthat area was observed by a two-beam microscope using, as a lightsource, white light of a halogen lamp filtered through a G filter.

As observed by the two-beam microscope, the coarse projections areobserved as contour lines of closed interference fringes, and the higherthe projections, the more the number of contour lines, i.e. as aprojection becomes high, the degree of fringes increases in the order ofa single circle, a double circle, . . . .

The number is visually counted and converted to the number in 10 cm² ofthe film surface, which is taken as the number of coarse surfaceprojections in the film.

L1: one wherein the degree of fringes is single

L2: one wherein the degree of fringes is double

L3: one wherein the degree of fringes is triple Under such measurementconditions:

L1 means one having a height of from 0.27 μm to less than 0.54 μm;

L2 means one having a height of from 0.54 μm to less than 0.81 μm; and

L3 means one having a height of from 0.81 μm to less than 1.08 μm.

Evaluation of Forming Fibers

The polyester resin chips were dried and then supplied to an extrudertype spinning machine, and using a spinneret having circular holes eachhaving a diameter of 0.6 mm, continuous extrusion was carried out at aspinning temperature of 295° C. for 48 hours, whereby presence orabsence of deposition of spinneret contaminants around the dischargeportions of the spinneret was visually confirmed.

Example 5-1

A polyethylene terephthalate was continuously produced by means of acontinuous polymerization apparatus as shown in FIG. 2, comprising aslurry preparation tank composed of a single agitation tank,esterification reactors composed of two agitation tanks connected inseries, and a total of three melt polycondensation reactors comprisingan agitation tank and two horizontal plug flow type reactors followingit.

To the slurry preparation tank 1, ethyl acid phosphate in such an amountthat 9 ppm of phosphorus atoms would remain per 1 kg of the formedpolyester resin, and terephthalic acid and ethylene glycol, weresupplied so that the ratio of terephthalic acid:ethylene glycol=865:485(weight ratio), to obtain a slurry. This slurry was continuouslysupplied to the first stage esterification reactor 2 and then to thesecond stage esterification reactor 3. The reaction conditions in theesterification reactors were adjusted to be a temperature of 260° C. anda relative pressure of from 50 to 5 KPa (from 0.5 to 0.05 kg/cm²G) in anitrogen atmosphere, and the esterification ratio in the first stageesterification reactor was 85%, and the esterification ratio in thesecond stage esterification reactor was 95%.

At that time, from an upper pipe provided on the second stageesterification reactor 3, magnesium acetate tetrahydrate wascontinuously supplied in such an amount that 30 ppm of magnesium atomswould remain per 1 kg of the formed polyester resin.

The esterification reaction product was continuously supplied via aconduit 5 to the first stage melt polycondensation reactor 6, then tothe second stage melt polycondensation reactor 7 and then to the thirdmelt polycondensation reactor 8. At an intermediate point of the conduit5, tetrabutyl titanate in such an amount that 2.0 ppm of titanium atomswould remain per 1 kg of the formed polyester resin, and antimonytrioxide in such an amount that 90 ppm of antimony atoms would remainper 1 kg of the formed polyester resin, were continuously added to theesterification reaction product via a conduit 4.

The reaction conditions in the melt polycondensation reactors were suchthat in the first stage, the temperature was 270° C. and the absolutepressure was 2.6 KPa (20 Torr), in the second stage, the temperature was278° C. and the absolute pressure was 0.5 KPa (4Torr), and in the thirdstage, the temperature was 280° C. and the absolute pressure was 0.3 KPa(2 Torr), and the total polymerization time was three hours and 30minutes. The melt polycondensation reaction product was extruded fromthe die in the form of a strand, cooled and solidified, and then cut bya cutter to obtain melt polymerized chips having an average weight of 24mg each. The intrinsic viscosity of such chips was 0.65 dl/g, the numberof particles in the interior of the resin was 5.5 particles/0.01 mm³,the content of diethylene glycol component was 1.5 mol % based on thetotal diol component, the carboxylic acid terminal number was 35equivalents/t, and value b in the Hunter's color coordinate was 1.5.Further, the obtained chips were subjected to the measurement of thevolume resistivity, evaluation of formation of a film and evaluation offorming fibers. The analytical values and evaluation results are shownin Table 5.

Examples 5-2 to 5-4

A polyester resin was obtained in the same manner as in Example 5-1except that the amount of ethyl acid phosphate added was changed so thatthe amount of phosphorus atoms per 1 kg of the formed polyester resinwould be the remaining amount shown in Table 5. The analytical valuesand evaluation results are shown in Table 5.

Examples 5-5 to 5-7

A polyester resin was obtained in the same manner as in Example 5-1except that the amount of antimony trioxide added was changed so thatthe amount of antimony atoms per 1 kg of the formed polyester resinwould be the remaining amount shown in Table 5. The analytical valuesand evaluation results are shown in Table 5.

Examples 5-8 to 5-10

A polyester resin was obtained in the same manner as in Example 5-1except that the amount of ethyl acid phosphate and the amount ofantimony trioxide added, were changed so that the amounts of phosphorusatoms and antimony atoms, per 1 kg of the remaining polyester resin,would be the remaining amounts shown in Table 5 respectively. Theanalytical values and evaluation results are shown in Table 5.

Examples 5-11 to 5-12

A polyester resin was obtained in the same manner as in Example 5-1except that the amount of magnesium acetate tetrahydrate added waschanged so that the amount of magnesium atoms per 1 kg of the formedpolyester resin would be the remaining amount shown in Table 5. Theanalytical values and evaluation results are shown in Table 5.

Example 5-13

A polyester resin was obtained in the same manner as in Example 5-1except that the type of the phosphorus compound added was changed toorthophosphoric acid. The analytical values and evaluation results areshown in Table 5.

Comparative Example 5-1

The esterification apparatus used was a three stages perfect mixing tanktype continuous esterification reaction apparatus which comprises afirst esterification reactor provided with a stirring means, a partialcondenser, a feed inlet and a product outlet and a second esterificationreactor wherein the interior of the reactor is divided into two tanks,each reaction tank being provided with a stirring means, a partialcondenser, a feed inlet and a product outlet. An EG slurry of TPA havingthe molar ratio of EG to TPA adjusted to 1.7, was continuously suppliedto a system in the first esterification reactor where the reactionproduct was present. Simultaneously, an EG solution of magnesium acetatetetrahydrate was continuously supplied from an inlet separate from theinlet for the EG slurry of TPA, so that Mg atoms would be 0.82 mol per 1ton of the formed polyester resin (i.e. about 20 ppm based on the formedpolyester resin, and the reaction was carried out under normalpressure-at a temperature of 255° C. for an average retention time offour hours. This reaction product was continuously withdrawn out of thesystem and supplied to the first tank of the second esterificationreactor and continuously withdrawn from the second tank. For thetransfer from the first tank to the second tank, an overflow system wasemployed. From the inlet of the first tank, an EG solution of phosphoricacid in such an amount that P atoms would be 0.16 mol (about 5 ppm) per1 ton of the formed polyester resin, and from the inlet of the secondtank, an EG solution of phosphoric acid in such an amount that P atomswould be 0.60 mol (about 19 ppm) per 1 ton of the formed polyesterresin, were continuously added and reacted under normal pressure at atemperature of 260° C. for an average retention time of 2.5 hours ineach tank.

Then, the esterification reaction product was continuously withdrawnfrom the second esterification reactor and continuously supplied to acontinuous polycondensation reactor of two stages provided with astirring means, a partial condenser, a feed inlet and a product outlet.From a pipe for supplying a polycondensation catalyst, connected to thetransportation pipe for the esterification reaction product, an EGsolution of antimony trioxide in such an amount that Sb atoms would be0.66 mol (about 80 ppm) per 1 ton of the formed polyester resin, and anEG solution of tetrabutyl titanate in such an amount that Ti atoms wouldbe 0.06 mol (about 3 ppm) per 1 ton of the formed polyester resin, weresupplied to the esterification reaction product, and in theabove-mentioned continuous polycondensation reactor, polycondensationwas carried out at about 270° C. under reduced pressure. The totalpolymerization time was 3 hours and 19 minutes. The meltpolycondensation product was extruded from a die in the form of astrand, cooled and solidified, and then cut by a cutter to obtain meltpolymerized chips having an average weight of 24 mg each. The intrinsicviscosity of the chips was 0.52 dl/g, the number of particles in theinterior of the resin was 5.5 particles/0.01 mm³, the content of thediethylene glycol component was 2.8 mol % based on the total diolcomponent, the carboxylic acid terminal number was 30 equivalents/t, andvalue b in the Hunter's color coordinate was 1.0. Further, the obtainedchips were subjected to the measurement of the volume resistivity, theevaluation of formation of a film and the evaluation of formation offibers. The analytical values and evaluation results are shown in Table5.

Comparative Example 5-2

A polyester resin was obtained in the same manner as in Example 5-1except that no tetrabutyl titanate was added, the amount of ethyl acidphosphate to be added and the amounts of magnesium acetate tetrahydrateand antimony trioxide, were adjusted so that phosphorus atoms, magnesiumatoms and antimony atoms would be in the remaining amounts as identifiedin Table 5, respectively, per 1 kg of the formed polyester resin, andthe magnesium acetate tetrahydrate and the antimony trioxide were mixedand continuously added via a conduit 4 to the esterification reactionproduct in an intermediate point of the conduit 5. The analytical valuesand evaluation results are shown in Table 5.

Comparative Example 5-3

100 parts of dimethyl terephthalate and 70 parts of ethylene glycol weresubjected to ester exchange reaction by adding, as ester exchangecatalysts, calcium acetate monohydrate and magnesium acetatetetrahydrate so that calcium atoms and magnesium atoms would be in theremaining amounts as identified in Table 5, respectively, per 1 kg ofthe formed polyester resin, and further, after 20 minutes from theinitiation of distillation of methanol, adding antimony trioxide so thatantimony atoms would be in the remaining amount as shown in Table 5 per1 kg of the formed polyester resin. Then, trimethyl phosphate (TMP) wasadded so that phosphorus atoms would be in the remaining amount asidentified in Table 5 per 1 kg of the formed polyester resin, thereby tosubstantially terminate the ester exchange reaction. Further, tetrabutyltitanate was added so that titanium atoms would be in the remainingamount as identified in Table 5 per 1 kg of the formed polyester resin,and then continuously, polycondensation was carried out in a hightemperature high vacuum condition in accordance with a usual method. Themelt polycondensation reaction product was extruded from a die in theform of a strand, cooled and solidified, and then cut by a cutter toobtain melt polymerized chips having an average weight of 24 mg each.The obtained chips were subjected to the measurement of the volumeresistivity, the evaluation of forming a film and the evaluation offorming fibers. The analytical values and evaluation results are shownin Table 5.

Comparative Example 5-4

254 parts by weight of bis(β-hydroxyethyl)terephthalate and 83 parts byweight of terephthalic acid were introduced into a polymerizationreactor having a rectifying column and then heated to 250° C. withstirring while supplying a very small amount of nitrogen. During thisperiod, ethylene glycol was refluxed, only water formed, was distilledoff out of the system. When the ester exchange ratio reached 80%, ascalculated from the amount of water distilled, 1.7 parts by weight of aliquid solution in ethylene glycol of 2 wt % of antimony trioxide and0.12 wt % of tetrabutyl titanate, 3.3 parts by weight of a 5 wt %ethylene glycol solution of magnesium acetate (as metal atoms, antimony:100 ppm, titanium: 1 ppm, and magnesium: 65 ppm, based on the finallyobtainable polymer) and 1.3 parts by weight of a 5 wt % ethylene glycolsolution of trimethyl phosphoric acid (50 ppm as phosphorus atoms basedon the finally obtainable polymer) were introduced. Then, whilecontinuing heating and stirring, the pressure was gradually lowered, andover a period of about one hour, inside of the reactor was brought to ahighly vacuumed condition of not more than 5 torr. During this period,the temperature was raised to 285° C. In this state, polymerization wascontinued for 189 minutes since the pressure was brought to a highlyvacuumed condition of not more than 5 torr. The melt polycondensationreaction product was extruded from a die in the form of a strand, cooledand solidified, and then cut by a cutter to obtain melt polymerizedchips having an average weight of 24 mg each. The obtained chips weresubjected to the measurement of the volume resistivity, the evaluationof forming a film, and the evaluation of forming fibers. The analyticalvalues and evaluation results are shown in Table 5.

TABLE 5 Examples Amount of Sb eluted 5-1 5-2 5-3 (μg/resin) 0.12 0.140.12 Sb content (ppm) 90 90 90 T content (ppm) 2 2 2 Ti content (ppm) 22 2 M′ content (ppm)* 30 30 30 Mg content (ppm) 30 30 30 Ca content(ppm) 0 0 0 P content (EAP) (ppm) 9 12 6 P content (TMP) (ppm) 0 0 0 Pcontent (H3P04) (ppm) 0 0 0 Sb/P (weight ratio) 10.0 7.5 15.0 Mg/P(weight ratio) 3.33 2.50 5.00 Production process B B B Polymerizationtime 3:30 3:40 3:20 hours:minutes Copolymerized amount of DEG 1.5 1.61.4 (mol %) Physical properties of resin Intrinsic 0.65 0.65 0.65viscosity (dl/g) Color coordinate 1.5 1.2 2.0 b Carboxylic acid 35 30 40terminal number (AV) (equivalents/ton resin) Number of 5.5 7.3 3.6particles in the interior of resin particles/0.01 mm³ Volume 3.0E + 072.3E + 07 4.5E + 07 resistivity Ω.cm Evaluation of film Number ofprojections on the surface Number of F1 51 67 34 Number of F2 1 2 1Number of F3 0 0 0 Evaluation of fibers Contamination of No No Nospinneret Examples Amount of Sb eluted 5-4 5-5 5-6 (μg/resin) 0.11 0.10.15 Sb content (ppm) 90 70 120 T content (ppm) 2 2 2 Ti content (ppm) 22 2 M′ content (ppm)* 30 30 30 Mg content (ppm) 30 30 30 Ca content(ppm) 0 0 0 P content (EAP) (ppm) 3 9 9 P content (TMP) (ppm) 0 0 0 Pcontent (H3P04) (ppm) 0 0 0 Sb/P (weight ratio) 30.0 7.8 13.3 Mg/P(weight ratio) 10.00 3.33 3.33 Production process B B B Polymerizationtime 3:10 4:30 2:37 hours:minutes Copolymerized amount of DEG 1.3 1.71.3 (mol %) Physical properties of resin Intrinsic 0.65 0.65 0.65viscosity (dl/g) Color coordinate 3.7 1.9 1.1 b Carboxylic acid 45 35 20terminal number (AV) (equivalents/ton resin) Number of 1.8 4.3 7.3particles in the interior of resin particles/0.01 mm³ Volume 9.0E + 073.0E + 07 3.0E + 07 resistivity Ω.cm Evaluation of film Number ofprojections on the surface Number of F1 18 40 67 Number of F2 0 1 2Number of F3 0 0 0 Evaluation of fibers Contamination of No No Nospinneret Examples Amount of Sb eluted 5-7 5-8 5-9 (μg/resin) 0.41 0.110.12 Sb content (ppm) 180 40 40 T content (ppm) 2 4.5 4.5 Ti content(ppm) 6 4.5 4.5 M′ content (ppm)* 30 30 30 Mg content (ppm) 30 30 30 Cacontent (ppm) 0 0 0 P content (EAP) (ppm) 9 6 3 P content (TMP) (ppm) 00 0 P content (H3P04) (ppm) 0 0 0 Sb/P (weight ratio) 20.0 6.7 13.3 Mg/P(weight ratio) 3.33 5.00 10.00 Production process B B B Polymerizationtime 1:45 3:20 3:10 hours:minutes Copolymerized amount of DEG 1.1 1.41.3 (mol %) Physical properties of resin Intrinsic 0.65 0.65 0.65viscosity (dl/g) Color coordinate 0.8 4.6 8.3 b Carboxylic acid 14 26 25terminal number (AV) (equivalents/ton resin) Number of 10.9 1.6 0.8particles in the interior of resin particles/0.01 mm³ Volume 3.0E + 074.5E + 07 9.0E + 07 resistivity Ω.cm Evaluation of film Number ofprojections on the surface Number of F1 100 16 9 Number of F2 3 0 0Number of F3 0 0 0 Evaluation of fibers Contamination of No No Nospinneret Examples Amount of Sb eluted 5-10 5-11 5-12 5-13 (μg/resin)0.14 0.1 0.13 0.24 Sb content (ppm) 120 90 90 90 T content (ppm) 1.5 2 22 Ti content (ppm) 1.5 2 2 2 M′ content (ppm)* 30 15 60 30 Mg content(ppm) 30 15 60 30 Ca content (ppm) 0 0 0 0 P content (EAP) (ppm) 18 9 90 P content (TMP) (ppm) 0 0 0 0 P content (H3P04) (ppm) 0 0 0 9 Sb/P(weight ratio) 6.7 10.0 10.0 10.0 Mg/P (weight ratio) 1.67 1.67 6.673.33 Production process B B B B Polymerization time 4:00 3:45 3:15 3:51hours:minutes Copolymerized amount 1.6 1.5 1.5 1.5 of DEG (mol %)Physical properties of resin Intrinsic 0.65 0.65 0.65 0.65 viscosity(dl/g) Color coordinate 0.7 1.7 1.3 1.8 b Carboxylic acid 31 35 46 35terminal number (AV) (equivalents/ton resin) Number of 14.6 5.5 5.5 13.7particles in the interior of resin particles/0.01 mm³ Volume 1.5E + 077.5E + 06 1.2E + 08 3.0E + 07 resistivity Ω.cm Evaluation of film Numberof projections on the surface Number of F1 133 51 51 124 Number of F2 41 1 4 Number of F3 0 0 0 0 Evaluation of fibers Contamination of No NoNo No spinneret Comparative Examples Amount of Sb eluted 5-1 5-2 5-3 5-4(μg/resin) 1.8 1.5 1.2 1.9 Sb content (ppm) 80 180 47 100 T content(ppm) 3 — 5 1 Ti content (ppm) 3 — 5 1 M′ content (ppm)* 24 57 114 65 Mgcontent (ppm) 24 57 47 65 Ca content (ppm) 0 0 67 0 P content (EAP)(ppm) 0 90 0 50 P content (TMP) (ppm) 0 0 40 0 P content (H3P04) (ppm)20 0 0 0 Sb/P (weight ratio) 4.0 2.0 1.2 2.0 Mg/P (weight ratio) 1.200.63 1.18 1.30 Production process E E D E Polymerization time 3:19 3:303:03 6:20 hours:minutes Copolymerized amount 2.8 1.9 1.7 1.9 of DEG (mol%) Physical properties of resin Intrinsic 0.52 0.65 0.60 0.62 viscosity(dl/g) Color coordinate 1.0 0.3 0.8 0.2 b Carboxylic acid 30 30 50 50terminal number (AV) (equivalents/ton resin) Number of 27.0 122.0 54.068.0 particles in the interior of resin particles/0.01 mm³ Volume 8.6E +06 1.1E + 07 4.0E + 07 2.5E + 07 resistivity Ω.cm Evaluation of filmNumber of projections on the surface Number of F1 244 1099 487 613Number of F2 8 36 16 20 Number of F3 3 12 5 7 Evaluation of fibersContamination of Yes Yes Yes Yes spinneret *M′ indicates the sum ofcontents of Mg and Ca.

Industrial Applicability

According to the present invention, it is possible to provide apolyester resin which is polycondensed in the presence of an antimonycompound and whereby elution of antimony is suppressed, and a processfor producing a polyester resin, whereby such a polyester resin cansuitably be obtained.

The entire disclosures of japanese patent application no. 2001-16535filed on Jan. 25, 2001 and Japanese patent application No. 2001-297454filed on Sep. 27, 2001 including specifications, claims, drawings andsummaries are incorporated herein by reference in their entireties.

What is claimed is:
 1. A polyester resin produced by polycondensing adicarboxylic acid component containing an aromatic dicarboxylic acid orits ester-forming derivative as the main component and a diol componentcontaining ethylene glycol as the main component in the presence of atleast an antimony compound and a phosphorus compound, via anesterification reaction or an ester exchange reaction, which ischaracterized in that the amount of antimony eluted when immersed in hotwater of 95° C. for 60 minutes in the form of particles having a numberaverage particle weight of 24 mg, is not more than 1 pg per 1 g of thepolyester resin, as antimony atoms (Sb).
 2. The polyester resinaccording to claim 1, characterized in that the difference(ΔAA=AA_(s)−AA_(o)) between the acetaldehyde content (AA_(s); ppm) in amolded product when injection-molded at 280° C. and the acetaldehydecontent (AA_(o); ppm) before the injection molding, is not more than 20ppm.
 3. The polyester resin according to claim 2, wherein the ratio(Sb/P) of the content (weight ppm) as antimony atoms (Sb) of theantimony component to the content (weight ppm) as phosphorus atoms (P)of the phosphorus component in the polyester resin, is from 6.0 to 30.4. The polyester resin according to claim 2, wherein the content asphosphorus atoms (P) of the phosphorus component in the polyester resinis from 0.1 to 20 weight ppm.
 5. The polyester resin according to claim2, which is poly-condensed in the coexistence of a compound of at leastone metal element selected from the group consisting of Groups 1A andIIA of the Periodic Table, zinc, aluminum, gallium, germanium, titanium,zirconium, hafnium, manganese, iron and cobalt, and wherein the totalcontent as metal atoms (M) of such metal element components in thepolyester resin, is from 0.1 to 100 weight ppm.
 6. The polyester resinaccording to claim 5, wherein the coexistent compound is a magnesiumcompound, and the ratio (Mg/P) of the content (weight ppm) as magnesiumatoms (Mg) of the magnesium component to the content (weight ppm) asphosphorus atoms (P) of the phosphorus component in the polyester resin,is from 1.1 to 3.0.
 7. The polyester resin according to claim 5, whereinthe coexistent compound is a magnesium compound, and the content asmagnesium atoms (Mg) of the magnesium component in the polyester resinis from 0.1 to 30 weight ppm.
 8. The polyester resin according to claim5, wherein the coexistent compound is a titanium compound, and thecontent as titanium atoms (Ti) of the titanium component in thepolyester resin is from 0.25 to 10 weight ppm.
 9. The polyester resinaccording to claim 2, wherein the content as antimony atoms (Sb) of theantimony component in the polyester resin is from 10 to 250 weight ppm.10. The polyester resin according to claim 2, wherein the atomic valenceof phosphorus element in the phosphorus component is trivalent.
 11. Amolded product obtainable from the polyester as defined in claim
 1. 12.The polyester resin according to claim 1, wherein the ethylene glycolcomponent is at least 96 mol % of the total glycol component, thediethylene glycol component is not more than 2.5 mol % of the totalglycol component, the terephthalic acid component is at least 98.5 mol %of the total acid component, the intrinsic viscosity IV is from 0.65 to0.90 dl/g, and the temperature-lowering crystallization temperature Tc₂is from 150 to 200° C.
 13. The polyester resin according to claim 12,wherein the acetaldehyde content AA and the carboxylic acid terminalnumber AV satisfy the following formulae (1) and (2), respectively: AA≦3(ppm)  (1) AV: 1 to 40 (equivalents/ton resin) (2).
 14. The polyesterresin according to claim 12, characterized in that the content P ofphosphorus atoms and the content Sb of antimony atoms satisfy thefollowing formula (3): 6.0≦Sb/P≦20  (3) (Sb: content of antimony atoms(weight ppm based on the polyester resin), P: content of phosphorusatoms (weight ppm based on the polyester resin)).
 15. The polyesterresin according to claim 12, characterized in that the content P ofphosphorus atoms satisfies the following formula (4): P≦14  (4) (P:content of phosphorus atoms (weight ppm based on the polyester resin).16. The polyester resin according to claim 13, characterized in that itcontains, as a polycondensation catalyst, a compound of at least onemetal element selected from the group consisting of Groups 1A and IIA ofthe Periodic Table, zinc, aluminum, gallium, germanium, titanium,zirconium, hafnium, manganese, iron and cobalt, and the total content Mof the metal atoms satisfies the following formula (5): 0.1≦M≦100(weight ppm based on the polyester resin) (5).
 17. The polyester resinaccording to claim 16, characterized in that the metal atoms aremagnesium, and the content Mg of magnesium atoms and the content P ofphosphorus atoms satisfy the following formula (6): 1.1≦Mg/P≦3.0  (6)(Mg: content of magnesium atoms (weight ppm based on the polyesterresin), P: content of phosphorus atoms (weight ppm based on thepolyester resin)).
 18. The polyester resin according to claim 16,characterized in that the metal atoms are magnesium, and the content ofmagnesium atoms is from 3 to 25 ppm.
 19. The polyester resin accordingto claim 16, characterized in that the metal atoms are titanium, and thecontent of titanium atoms is from 0.25 to 10 ppm.
 20. The polyesterresin according to claim 12, characterized in that the content Sb ofantimony atoms satisfies the following formula (7): 10≦Sb≦250  (7) (Sb:content of antimony atoms (based on the polyester resin ppm).
 21. Amolded product obtainable from the polyester resin as defined in claim20.
 22. The molded product according to claim 21, which is a hollowmolded product for a non-carbonated beverage.
 23. The polyester resinaccording to claim 1, which contains an ethylene terephthalate unit asthe main repeating constituting unit, characterized by satisfying thefollowing characteristics (A), (B) and (C): (A) after formed into amolded product, the temperature-rising crystallization temperature (Tc₁)is at least 155° C., and the temperature-lowering crystallizationtemperature (Tc₂) is at most 180° C. or not observed, (B) the difference(ΔAA=AA_(s)−AA_(o)) between the acetaldehyde content (AA_(s); ppm) in amolded product after injection molding at 280° C. and the acetaldehydecontent (AA_(o); ppm) before the injection molding, is not more than 15ppm, and (C) when an injection-molded sheet having a thickness of 1 mmis immersed in a 0.2 wt % sodium hydroxide aqueous solution at 25° C. insuch a state that it is fixed along the outer circumference of acylinder having a diameter of 32 mm, the environmental stress rupturetime is at least 10 minutes.
 24. The polyester resin according to claim23, which satisfies the following characteristics (D), (E) and (F): (D)the proportion of diethylene glycol in the diol component in the resinis not more than 2.0 mol %, (E) the carboxylic acid terminal number (AV)is from 20 to 50 equivalents/ton resin, and (F) the intrinsic viscosity[η] is from 0.75 to 1.0 dl/g.
 25. The polyester resin according to claim23, which satisfies the following characteristic (G): (G) the absorbanceat a wavelength of 1,000 nm in the form of an injection-molded platehaving a thickness of 4 mm, is from 0.04 to 0.20.
 26. The polyesterresin according to claim 23, which contains a titanium compound andwherein the content (ppm) as antimony atoms (Sb) and the content (ppm)as titanium atoms (Ti) satisfy the following formulae: 10≦Sb≦200 0<Ti≦10150≦100Ti+Sb≦1,200.
 27. A molded product obtainable from the polyesterresin as defined in claim
 23. 28. The polyester molded product accordingto claim 27, which is a hollow product for a carbonated beverage.
 29. Aprocess for producing a polyester resin, which comprises polycondensinga dicarboxylic acid component containing an aromatic dicarboxylic acidor its ester-forming derivative as the main component and a diolcomponent containing ethylene glycol as the main component,characterized in that a catalyst is added to the reaction system so thatthe following respective atoms derived from the catalyst will becontained in the following concentration ranges based on the obtainablepolyester resin: 0<T≦50 ppm 10≦Sb≦250 ppm 0.1≦P200 ppm 6.0≦Sb/P≦30 (inthe above formulae, T is the total concentration (ppm) of at least onetype of atoms selected from the group consisting of titanium atoms,hafnium atoms and zirconium atoms in the resin, Sb is the concentration(ppm) of antimony atoms in the resin, and P is the concentration (ppm)of phosphorus atoms in the resin).
 30. The process for producing apolyester resin according to claim 29, characterized in that a catalystis added to the reaction system so that the following respective atomsderived from the catalyst will be contained within the followingconcentration ranges based on the obtainable polyester resin: 0.1≦M≦200ppm 1.1≦M/P≦15 (M is the total content (ppm) of at least one type ofmetal atoms selected from the group consisting of Group IA metal atoms,Group IIA metal atoms, manganese atoms, iron atoms and cobalt atoms).31. The process for producing a polyester resin according to claim 29,characterized in that the dicarboxylic acid component and the diolcomponent are subjected to an esterification reaction, and at a stagewhere the esterification ratio is less than 90%, a phosphorus compoundis added to the reaction mixture containing the esterification reactionproduct, and after the esterification ratio has reached at least 90%, atleast one metal atom compound selected from the group consisting of aGroup IA element compound, a Group IIA element compound, a manganesecompound, an iron compound and a cobalt compound, is added, andthereafter, at least one compound selected from the group consisting ofa titanium compound, a zirconium compound, a hafnium compound, analuminum compound, a zinc compound, a gallium compound and a germaniumcompound, is added.